Starting Again

I`m on the last chapter of BG2 and am looking forward to starting again. I`ve missed out on loads of quests and I`d also like to start with a mage of some sort. First time round I used a Fighter-Berserker (female).
It was all right but I didn`t get any romances. I didn`t start to get to grips with a lot of the spells and magic until the seventh chapter (I`ve just been blatted by that bloody dragon again).
What I`d like to know is if I use a multi-player game, how does it work? With the normal game, in the first chapter I have Jaheira. Minsc and Imoen with me. Would these be replaced with characters I`d invented? (Except Imoen, I suppose).
Can I do without Jaheira? That is one boring old fart of a dame! And those awful ears!
Speaking of chapter seven, is it just me or is it normal that you can`t save game for such a long time? I`ve done mages, golems and others whose names I cant spell, and ended up in front of this bloody great dragon without being able to save.
Cheers