Activate? Yes. Deactivate?...maybe?. If I remember correctly, I made it work by giving a destiny in each tier. Depending on your current tier, it gives the destiny and erases the one from the previous T. I've got no idea what happens if you take out a mod that gave a destiny. It could leave a blank destiny that doesn't do anything that the game checks, realices it does nothing and just ignores, tries to do something and breaks, leave you with the buff even without the mod, etc...no idea how it interacts.

As long as you don't save the game (manually or by passing a month) you could try taking it out, killing an npc and seeing if it breaks anything.

Still, the best way to try it is with a new character you don't really care about :P

Question: can I activate and Unactivated mid-game?

Have you tried the game with only this mod enabled and that still happens? I still use this mod in every one of my games and I haven't had that problem.
Unless they changed something in the last week, which I think it was the last time I played, I've got no idea what it could be. If it happens with only this mod enabled I'll have to check if they changed something in the mod maker.

it seems if I use this mod stranger won't come up to me to talk/gift/spar etc unless they already have connection with my character before (friends/enemies/master or student)

This sounds really useful, thanks for sharing it.