When I played before, I played a single-class character. I've been trying out different types of players this time but haven't gone too far into the game. My question is, if I dual, can I just not level up after say Level 7 until I get enough points to dual? At least you would have a level 7 Player at the end rather than a weaker dual class character not yet with sufficient levels to gain back the old skills. Is that considered against the spirit of the game or does the game wipe the points out before transferring to BG2?
The game is exp capped. That means you can have 161000exp in BG1, 2.8mio exp in BG2 and 8mio exp in ToB. Each class needs a different amount of exp for each level. You must plan your classes in a way that: (exp for level x old class) + (exp for level x+1 new class) < (exp cap for your game)
When you get more than 2.8mio exp in bg2 you get an extra ability at each level up.
You must also know that you cannot use any skill of the old class until your new class has a higher level than your old class. And you will never get better in anything of your old class again.
My advice: Do not dual class in bg1. You will be unable to use the skills of your old class for most of the game. If you want to dual class, play a single class through bg1 and dual class at the beginning of bg2, when your char gets level 9 (fighter, ranger) or 10 (thief). You get max HP, most of the importand skills and you will get enough exp for the second class fast.
Of course, it must be human and you must regard the stat and alignment restrictions mentioned above.
@Hickory: You are correct. I think my fighters had 5/2 attacs at high levels (1 base attac + 0.5 at level 7 + 0.5 at level 13 + 0.5 weapon specialisation).
I don´t know how it is done with x.5 attacs per round. Does it mean that you have x attacs every round and x+1 attacs every second round?