Netflow Upgrade and Migration (huge db) v6 --> v7

Hello, In my company are planning move from Netflow 6.0 to 7.6.... I'm just start working with Netflow, so I hope someone can help me with these Issues.

1. Is the version 7.6 the latests stable one in the v7 family ?? Can I install the v8 version with my current license ?

2. We are planning some minor-tests preparing for the big upgrade, the main issue is if we can migrate all the database from version 6 to 7 without problem, I read some post where talks about migration between same build version, and nothing about different build and version. What is the best procedure for migrate the database ? using the .bak method or coping the /data folder method. some extra recommendation ?

3. My backup file has actually close to 14 GB, and usually takes close to 8 hours to be complete. The /data folder has close to 39 GB. This affect in some point the migration or the method for do it ?

BTW is running over Windows 2003 Server (if is relevant). And information of the license: Max no. of interfaces:600, Professional license, without expiration

Best Regards,
Wilson T.