i got to a boss that one hit killed plutia. after that the game just locked up. i did grind and my characters was around level 15 but, i need to be level 30 to get through chapter 1.

A certain fight (which I think is in Ch 2 IIRC) is a vertical cliff in so far as having to grind to at least lvl 25 (so you have access to EXE Drive moves). Once that particular fight is done there is no real need to grind levels for the rest of the game IMO

Sucks that the game crashed - the best place to grind though is outlined HERE

Yes I agree with you. The first time I played the game, found this game terribly difficult, even with the weaken enemies and some grinding, a normal monster damage can go from two digits to +1500. I still have Nightmares from the last 2 battles on Chapter 2...
I always find funny how some people would recommend this game to newcomers to the series, knowing that it's very difficult and sometimes frustrating. For me, the best one to start would be RB2 or Original VII (this is the one what introduced me to this series) since they are somehow more forgiving than RB1 (this game is great too).
Well, back to topic, you can use the Oracles, Kei Mina and Chika (don't know if they are incluided on the base game) since they are somehow overpowered (they have +1000 vit and +700 str just at lv 1) most attacks to them will be 0 damage, even from bosses at ste beginning of the game. Now remember than some bosses from half/near the end ef the game (especially the ones that use debuffs) are quite powerful, so even with them, you should grind some levels before any event point/boss fight.