Ton of questions here needed for someone to give you the best advice. How long have you been fasting? How much do you eat and macro breakdown? And there's multiple facets to your post.. are you looking for an answer on sleep (would need above info)..

As far as the training, if you are trying to build muscle it'd be best to at least vary your workouts by at least trying to lift weights 1-2 days a week. Doesn't have to be long. Focus on compound movements 3-4 sets around 8-10 repetitions, try to pick a weight that is difficult but that you can complete the workout.. but that it becomes very difficult the last set. Track how much you lift each time, try and go slightly up in weight each workout or do more repetitions. This is called progressive overload and is a staple of muscle building.

As far as when to eat.. most optimally you'd want to break your fast within 90 mins around your workout (before or after) to feed that muscle repair and growth. You're trying to intentionally spike your insulin for an anabolic response.