1) I was just wondering if my character levels are good enough to continue, or if I should just train some more. Im currently at Nibelheim on disc 1:
Cloud- Level 27
Red XIII- Level 25
Barret- Level 25
Cait Sith- Level 23
Tifa- Level 22
Aeris- Level 21

Does that seem about right?

2) Im reading this guide right now and it sais that in Shinra mansion, the boss there is optional. Does that mean I can just skip that part, or do I have to go there to continue my game?