As discussed in A-MQ7 migration doc meeting:

In A-MQ6 karaf is the default deployment of A-MQ6. People migrating from A-MQ6 may be confused regarding their existing karaf containers. I believe it should be stated explicitly in the migration guide

1) the recommended deployment approach for customers migrating from 6.x - I think this is using a standalone container (but that would need to be confirmed with eng). Also strongly encourage users to use the recommended path.

2) Is it technically possible to deploy in karaf container