Cisco ASA 5200 and ISA 2k4

Hello. Recently I have decided to purchase and add a Cisco ASA 5200 to our existing network which currently only exists of ISA 2k4 serving as both a firewall and web proxy. I am wanting to keep the ISA but have it only serve as a proxy (I have BT Webfilter installed on the ISA box) so I am definately wanting to keep the filtering product in place.  I have already started configuring the ASA firewall and will post the configuration below. Also, right now we have a flat network with no dmz for web servers, etc. I am wanting to incorporate and configure an interface on the new firewall for a DMZ to incluse 3-4 web servers as well as a couple of other Terminal servers accessible by the outside world through RDP. Right now our T1 terminates to a cisco 1720 series router. All internal hosts gateway point to the router address of 172.16.0.5. The router is configured to route all traffic to the ISA box 172.16.0.19.  Also if the config copied below looks horribly bad please don't hesitate to let me know what needs to be changed :)

Questions:

1.)  What is the most efficiant and easiest way to incorporate the new firewall while keeping the ISA box in place? What will I need to change on ISA to make it no longer serve as a firewall but only as a proxy & filtering.  Is there a wizard to change from a edge firewall to a back end? Will I just leave the clients gateway pointing to .5 (router) and then just change the internal interface of the cisco asa firewall to the old internal ip of the ISA box.. Right now we have a route command on the router (ip route 0.0.0.0 0.0.0.0 172.16.0.19) that routes all traffic to the isa box. So that is why I was thinking maybe just change the internal interfae of the cisco firewall to .19.

2.) Configuring DMZ --> Does anyone have a sample config that incorporates a DMZ so that I can see how the access-lists, and interface are set up?

3.) OWA/ActiveSync --> I have created my static entry and access-list for https. Does anything else need to be configured or added in order for OWA/ActiveSync to work properly? I am a bit confused because currently we have all the certs needed for OWA/ActiveSync residing on our ISA box itself. Where will the certs need to be now that the ISA box will not be serving as a firewall?

Here is my configuration on the ASA box thus far.

:
ASA Version 7.0(5)
!
hostname ASA
domain-name XXX
enable password
names
no dns-guard
!
interface GigabitEthernet0/0
 description outside interface - WAN
 shutdown
 nameif outside
 security-level 0
 ip address 66.xxx.xxx.xxx.xxx 255.0.0.0
!
interface GigabitEthernet0/1
 nameif INSIDE
 security-level 100
 ip address 172.16.0.19 255.255.224.0
!
interface GigabitEthernet0/2
 description DMZ
 shutdown
 security-level 10
 ip address 10.0.0.1 255.0.0.0
!
interface GigabitEthernet0/3
 shutdown
 no nameif
 no security-level
 no ip address
!
interface Management0/0
 shutdown
 no nameif
 no security-level
 no ip address
!
passwd
ftp mode passive
clock timezone cst -6
clock summer-time CDT recurring
dns domain-lookup INSIDE
access-list inbound extended permit tcp any host 66.xxx.xxx.xxx eq smtp
access-list inbound extended permit tcp any host 66. xxx.xxx.xxx eq www
access-list inbound extended permit tcp any host 66. xxx.xxx.xxx eq https
access-list inbound extended permit tcp any host 66. xxx.xxx.xxx eq ssh
access-list inbound extended permit udp any host 66. xxx.xxx.xxx eq dnsix
access-list inbound extended permit tcp any host 66. xxx.xxx.xxx eq domain
access-list inbound extended permit tcp any host 66. xxx.xxx.xxx eq pop3
access-list inbound extended permit tcp any host 66. xxx.xxx.xxx eq imap4
access-list inbound extended permit tcp any host 66. xxx.xxx.xxx eq 135
access-list inbound extended permit tcp any host 66. xxx.xxx.xxx eq 3389
access-list inbound extended permit tcp any host 66. xxx.xxx.xxx eq 3389
access-list inbound extended permit tcp any host 66. xxx.xxx.xxx eq 3389
access-list inbound extended permit tcp any host 66. xxx.xxx.xxx eq 3389
access-list inbound extended permit tcp any host 66. xxx.xxx.xxx eq www
access-list inbound extended permit tcp any host 66. xxx.xxx.xxx eq 1755
access-list inbound extended permit udp any host 66. xxx.xxx.xxx eq 1755
access-list inbound extended permit tcp any host 66. xxx.xxx.xxx eq https
access-list inbound extended permit tcp any host 66. xxx.xxx.xxx eq https
access-list inbound extended permit tcp any host 66. xxx.xxx.xxx eq https
access-list inbound extended permit tcp any host 66. xxx.xxx.xxx eq https
access-list inbound extended permit tcp any host 66. xxx.xxx.xxx eq www
access-list inbound extended permit tcp any host 66. xxx.xxx.xxx eq ssh
access-list inbound extended permit tcp any host 66. xxx.xxx.xxx eq www
access-list inbound extended permit tcp any host 66. xxx.xxx.xxx eq www
access-list inbound extended permit tcp any host 66. xxx.xxx.xxx eq www
access-list inbound extended permit tcp any host 66. xxx.xxx.xxx eq www
access-list nonat extended permit ip 172.16.0.0 255.255.224.0 192.168.30.0255.255.255.0
access-list 101 extended permit ip 172.16.0.0 255.255.224.0 any
pager lines 24
mtu outside 1500
mtu INSIDE 1500
ip local pool vpnremote 192.168.30.1-192.168.30.100
no failover
icmp permit any outside
icmp permit any INSIDE
no asdm history enable
arp timeout 14400
global (outside) 1 interface
nat (INSIDE) 0 access-list nonat
nat (INSIDE) 1 0.0.0.0 0.0.0.0
static (INSIDE,outside) 66. xxx.xxx.xxx 172.16.0.115 netmask 255.255.255.255
static (INSIDE,outside) 66. xxx.xxx.xxx 172.16.0.6 netmask 255.255.255.255
static (INSIDE,outside) 66. xxx.xxx.xxx 172.16.0.56 netmask 255.255.255.255
static (INSIDE,outside) 66. xxx.xxx.xxx 172.16.0.57 netmask 255.255.255.255
static (INSIDE,outside) 66. xxx.xxx.xxx 172.16.0.31 netmask 255.255.255.255
static (INSIDE,outside) 66. xxx.xxx.xxx 172.16.0.15 netmask 255.255.255.255
static (INSIDE,outside) 66. xxx.xxx.xxx 172.16.0.44 netmask 255.255.255.255
static (INSIDE,outside) 66. xxx.xxx.xxx 172.16.0.40 netmask 255.255.255.255
static (INSIDE,outside) 66. xxx.xxx.xxx 172.16.0.11 netmask 255.255.255.255
static (INSIDE,outside) 66. xxx.xxx.xxx 172.16.0.46 netmask 255.255.255.255
static (INSIDE,outside) 66. xxx.xxx.xxx 172.16.0.61 netmask 255.255.255.255
static (INSIDE,outside) 66. xxx.xxx.xxx 172.16.0.62 netmask 255.255.255.255
static (INSIDE,outside) 66. xxx.xxx.xxx 172.16.0.63 netmask 255.255.255.255
static (INSIDE,outside) 66. xxx.xxx.xxx 172.16.0.47 netmask 255.255.255.255
static (INSIDE,outside) 66. xxx.xxx.xxx 172.16.0.75 netmask 255.255.255.255
static (INSIDE,outside) 66. xxx.xxx.xxx 172.16.0.58 netmask 255.255.255.255
access-group inbound in interface outside
route outside 0.0.0.0 0.0.0.0 66. xxx.xxx.xxx 1
timeout xlate 3:00:00
timeout conn 1:00:00 half-closed 0:10:00 udp 0:02:00 icmp 0:00:02
timeout sunrpc 0:10:00 h323 0:05:00 h225 1:00:00 mgcp 0:05:00
timeout mgcp-pat 0:05:00 sip 0:30:00 sip_media 0:02:00
timeout uauth 0:05:00 absolute
aaa-server vpn protocol radius
aaa-server vpn host 172.16.0.2
 key ciscotest
group-policy VPNClients internal
group-policy VPNClients attributes
 split-tunnel-policy tunnelspecified
 split-tunnel-network-list value 101

split-dns value 172.16.0.2
 webvpn
group-policy vpn5520 internal
no snmp-server location
no snmp-server contact
snmp-server enable traps snmp authentication linkup linkdown coldstart
crypto ipsec transform-set FirstSet esp-3des esp-md5-hmac
crypto dynamic-map dyn1 1 set transform-set FirstSet
crypto dynamic-map dyn1 1 set reverse-route
crypto map mymap 1 ipsec-isakmp dynamic dyn1
crypto map mymap interface outside
isakmp identity address
isakmp enable outside
isakmp policy 1 authentication pre-share
isakmp policy 1 encryption 3des
isakmp policy 1 hash md5
isakmp policy 1 group 2
isakmp policy 1 lifetime 86400
isakmp nat-traversal  20
isakmp disconnect-notify
tunnel-group Remote type ipsec-ra
tunnel-group Remote general-attributes
 address-pool vpnremote

default-group-policy VPNClients
tunnel-group Remote ipsec-attributes
 pre-shared-key *
telnet timeout 5
ssh timeout 5
console timeout 0
!
class-map inspection_default
 match default-inspection-traffic
!
!
policy-map global_policy
 class inspection_default
  inspect dns maximum-length 512
  inspect ftp
  inspect h323 h225
  inspect h323 ras
  inspect netbios
  inspect rsh
  inspect rtsp
  inspect skinny
  inspect esmtp
  inspect sqlnet