IBM DS3300 and ESXi 4

I'm currently designing a new system using the IBM DS3300 and ESXi4.
I'd appreciate any remarks and suggestions before I'll continue with purchase this solution.

Storage : IBM DS3300 iSCSI Dual Controller with 10 X 450Gb SAS 15K.
VM : VMware ESXi 4
2 Servers : IBM x3550 (2 X QC E5420, 8Gb RAM, 2 X 146Gb SAS, Qlogic Dual Port iSCSI HBA)

Maximum Concurrent users : 15

Storage:
1. 2 X 450 RAID1, 1 X LUN for ESX1
2. 2 X 450 RAID1, 1 X LUN for ESX2
3. 6 X 450 RAID10, 2 X LUN for data inc. Exch., SQL, FS, ISO

ESX1:
VM1 = Server 2003 Std.(DC1) + Exch. + SQL, XOsoft for SW replication to DC2. Resources: 1CPU, 4Gb RAM
VM2 = Server 2003 + Blackberry software. Resources: 1CPU, 1Gb RAM

ESX2:
VM1 = Server 2003 Std.(DC2) + Exch. + SQL, XOsoft replica server. Resources: 1CPU, 4Gb RAM
VM2 = Server 2008 + TS + Office2007 + SAP Business One. Resources: 1CPU, 4Gb RAM

Backup:
Arcserve installed on ESX1/VM1 running D2D2T (External Tape) and DeDup. D2D will perform to local HDD on server.

Q's:
1. Running this configuration, will the users fill any performance problem?
2. Is there any reason way not connect the iSCSI HBA's from the storage to the servers directly? If we'll add a server, I'll add a switch.
3. Any problems with this configuration?
4. Using this HW, will I be able to use vMotion and HA, if I'll upgrade the VMware software?
5. Using this SW and HW, is it possible to change the size of a partition (add another HDD to and existing LUN)?
6. Are there any problems sharing the same VMFS running these SW and HW?
7. Are the RAID's and LUN's configuration correct?

Thanks.