A demo probably isn't necessary. However, I believe variables work the same way so I'll just tell you how to do the levelling thing. I'm not so sure about the damage thing anymore because I was planning to use common events, but I don't think you can call common events from skills in 2k3. I won't be able to do the weapon thing either, because I don't think you can access that information through events. Anyway, for the levelling:
First set all your stats to your base values with no growths (i.e. HP = 37, MP = 20, etc, with no growth). Then, make a one-time event called at the beginning of the game which sets a Variable (let's call it "Alex's Level") to 1. and then turn this off through a switch "Level Switch"
Next make a paralell process common event like this (I don't remember the way it looks, so feel free to ask questions if you don't know what any of the commands are (!= means Not Equal to)):
Control Variable: [Alex's Actual Level] = Hero Level [Alex]
Conditional Branch: Variable [Alex's Level] != Variable [Alex's Actual Level]
Control Variable [Alex's Level] + 1
Change Parameter: [Alex] HP + 32
Change Parameter: [Alex] MP + 20
Change Parameter: [Alex] Magic Power + 3
Change Parameter: [Alex] Strength - 9999 (this is because there is no way to set parameters. it has to be + or -)
Control Variables: [Alex Strength] = Variable [Alex's Level]
Control Variables: [Alex Strength] * Variable [Alex's Level]
Control Variables: [Alex Strength] - 1
Change Parameter: [Alex] Strength + Variable [Alex Strength]
Control Variable: [Alex Defense] = [Alex's Level]
Control Variable: [Alex Defense] mod 2
Conditional Branch: Variable [Alex Defense] = 0
Change Parameter: [Alex] Defense + 3
Else
Change Parameter: [Alex] Defense + 4
Branch END
Branch END
There, that should work. Post if you're having trouble. I wish I could help with the other problems :/