1. Maybe...if done right. Would be good if that was a game mode. Being able to choose if you want to be raided. Getting attacked all the time would be a pain, and fit for another game.
The start of the game could be an jerry-rigged alarm going off up in the woods. Maybe have your team, and the attackers, come in from spawn points around the map; maybe to leave you to prepare and set traps in preparation. Could use some of the proven code from freeform maybe. Beartraps sound amazing by the way; maybe an Ewok log trap too!
2. Heck NO. AI have proven to be stupid, time and time again. I want to go against real people. Real players are what make games like this what they are. Amazing and very unpredictable.
3. The ability to team up, even a tense pairing, would be amazing. Do you trust this stranger? Will he shoot you in the back, or will you both part ways amicably at the extraction point? Who gets the crate?
Team "modes" isn't what this game is about I believe. Having said that, it might be nice to have some backup if I was in a raid match.. Freeform teams could be awesome if done right. The gestures could be utilized in meeting and greeting (a wave), or sealing a tentative partnership (a handshake perhaps).