1) side from PSU pwedeng may ibang components ng PC mo ang nasira like the mobo, it may have gotten friend, check for any capacitors na lumobo, look for any burnt smell
2) 80+ PSUs of any brand is a good buy, bronze is ok for a basic rig
3) 80+ PSUs will cosdt a bit more than typical generic PSUs
4) 80+ rating is the efficiency rating of PSUs, 80+ simply means they are more than 80% efficient, waste less power and give off less heat, divided into Bronze, Silver and Gold the better the rating the more expensive