Do not. That would be bad.
Also, if you were running a Plex 1.40+ release before updating DSM, do not install PMS 1.29.2 from Synology Package Center. Due to database changes it is not compatible with PMS 1.40+.
Yes.
In addition to the FAQ linked by Tom, see this post: Struggling with migration from DSM 6 to DSM7 - #2 by FordGuy61.
In Step 6 it says it is OK to use the version in Package Center. That info is now outdated. As mentioned above, 1,29.2 is incompatible with 1.40+ releases.
