Presentation Server 4 and Citrix Secure Gateway

Guys!
Id love your help.

Im getting a bit confused on what needs to be NATTED on our firewall.

We have 5 internal citrix servers. All 5 have applications that users external to our network need access to.

Question/s:

Q. On our firewall, do we need to assign a public IP address to each citrix server, and nat this to their internal IP address?
External users will be using the web ica client, and I intend to set up citirx secure gateway.

Q. Does our internal data collector require an external public ip address, and thus natted on our firewall?

Q. For every server that external ica clients require access to, do these citrix servers require a public IP address.

The reasons I ask this is because I believe the ALTADDR command needs to be run on every citrix server, if they need to provide applications to external ica clients.

Does this mean then that if you had 100 Citrix Servers, all advertising applications for external users to use, that ALL of them need a public IP address?

Sorry for the questions.

Simon