Lifting weights helps with maintaining muscle from what I’ve heard.
Depends on the fast and how long. Intermittent fast definitely yes. 2-5 day fast yes5+ days and on I seen a video that one guy who experimented said to do 8/8 and then get out of gym. (8 reps / 8 sets) no more than that. Don’t exhaust your body while fasting. This is just to maintain and to keep your muscles alive while fasting.
You probably shouldn’t. For one thing, you WILL NOT BUILD ANY MUSCLE, you will INCREASE MUSCLE LOSS. If you are insistent on lifting while fasting you should break the fast with a well.balanced protein rich meal immediately after and again another few hours or so later. Say your male, and fasting to get to 200 lbs. Try eating atleast 180g of protein on workout days and the day after your lifting sessions or you will increase catabolism.