General 2000 & Exchange 5.5 question

(1) Can I have more than 1 subnet in the same W2K Domain?

(2) I have a MS Exchange 5.5 running in NT4 Domain, can I setup another Exchange 5.5 server in W2K Domain with the same server name? Is there any problems if I configure the IMS to connectto the same domain name (e.g. xxxxxx.com)?

(3) After running W2K ADMT (active directory migration tool), both NT4 & W2K domain are both up & running. After this, do I upgrade NT4 PDC and the rest of BDCs & join the new W2K domain (native mode) inorder?

Any help would be appreciated.