Hello zimbrain's .

Now currently we are using
(Release 4.5.5_GA_838.RHEL4_64_20070518075936 RHEL5_64 FOSS edition ) open source edition. we are using zimbra master and replication servers. now we got permanant zimbra license for zimbra master server
( total mail boxes 75) .
i have some doubt's :
1) can i use same license for replication server also ?
2) total active accounts 75 execpt the mailman a/c's . are you counted mailman accounts ?
3) can i use same version of network edition or updated version while move from open source to network edition
4) how to update both zimbra master server and replication server OSS to NW edition
i know how to move OSS to NW for zimbra master . can i follow same steps for replication server also.

please any one can answer my question's and explain briefly