About Exchange Server 5.5

Hi,

I have two question about exchange server 5.5:
1) How to take backup of Exchange Server 5.5 I heard that EXMerge but it takes backup of mailboxes not whole exchange server.
2) I have two exchange servers both 5.5 and there is trust relation betweeen two but users on one exchange server can’t see GAL of other exchange server. What I have to change in my exchange so that they can see GAL.
Thanks.
Anurag.