2D idle game character movement/animations

I'm getting started with game development and I want to make a really simple 2d idle game, where two characters are facing each other and bash themselves to death. So here are few noob question:
1. I want to make enemies dash to each other during attack. Since their position through the game will be otherwise static, im thinking is it a good idea to put rigidbody with colliders on them and then move rigidbody through script, check collisions etc OR just play an animation moving character transform. Which one is better practice and WHY and what are other scenarios where each variant would be more relevant?
2. When attacking, i want to make an animation where character swing his weapon. After let's say 75% of swing animation is completed, i want then to deal damage (NOT at the start or end of animation)? How can i control it via the script? What is the best way to do this?
3. What is better way to persist player data (gold, current hp etc)? I've read about user preferences, but also about saving data with binary serializer and saving it on disk. Again, which is better, and what are (dis)advantages of each solution?
Cheers