Two very quick modding questions

[MisterBarca]

I am computer illiterate, but I want to make two qvery simple modifications to Civ 4. So I am wondering if anyone can give me a step by step instruction.

1. How do I change unit stats and special abilities?

2. How do I make units not lose all its XP over 10 when they upgrade? For instance, I'd go on a huge warpath and have a level 7 Praetorian or something. But then his XP drops to 10 once he becomes a Maceman. THis pisses me off!

Thanks in advance!