Or get the editor to do a respec on your characters. Valraven my first time through was a trial run i found lots of thngs to do differently my second and subsequent times there is no matching experience.
Oh yes stat and skill books are a must the fifth stone opens the hall of secrets every level up she stocks a 1 point stat book and a 3 point skill book. They are expensive . But well worth it in my estimation. Take all loot to her and save some items with barter and charisma and put em on when trading for the books.
When building a character i learned to look to your imperative, fighters should fight, mages should use spells, rogues should sneak backstab and steal, and rangers should shoot the enemy. Its fun to have multi class can do a lot characters but they dont tend to excel in any thing.
Dont worry my second party was far better and lots more fun to play.
You will beat this game, and i hope that you enjoy it and replay it a few times. I am on my ninth playthrough i think its even more fun than baldurs gates or icewind dales or temple of elemental evil.
As for help, i hope we did help. And if i helped then your sincerely welcome.
If i can do anything else pm me. Or post a question here.
Good luck and have fun.