Mine said "Most likely" so live in hope!
yes you can disable the internet using the adapter interface or etc.
Just making your PC not connect to the internet through whichever method you choose.
you don't HAVE to do this, it's just a way to make sure you aren't connected to UBI servers or doing something by accident online
That will not be added to the trainer.
V3 does this on purpose to help the users who had troubles with their registry not pointing to the correct install. Yes you will have to take 3 seconds to manually locate the root game folder when you want to use the trainer. We are leaving it this way to prevent problems in the future. If YOU pick the folder, then the trainer will have no problems locating the game and etc.