I have 8 ppl in my party right now...(I have recruited sparkle and Vi) In battles I have had ppl die and I always go back and reboot my saved game to try again...Is this nessecary? Should I let one go if he's weak or should I keep em' till the end?

The game can be completed with any number of party members, 1-8. If its your first time through, 6-8 is more than enough to survive all battles. Early party life is always difficult, but once you get to Trynton and beyond it should be no problem.

Or, if you're a practise junkie and use every character-building opportunity the game provides, you can get to the 'no problem' stage in Arnika already.