Rust!!!!!

I just got a 1993 240sx se fastback. Well overall the car doesn't have any rust on it. It's got a little on the the body here and there but that don't concern me as much. What I do worry about is the rust that is on the frame. Damn one side got a little hole that rusted through and the other side got a big A** rust hole.

Well my questions are:
Is it a big deal?
How should i go about to fix it?
Will it cost me alot to get it fixed?

get it fixed. you need to clean all the rust off and i mean ALL. then have someone weld steel braces around the holes. any holes in the floorpan not in the frame can be covered with just sheet metal welded in but since its a unibody car the frame needs to be solid.

1 & 2. yeah if its that bad just go to a reputable body shop to get it done the right way

3.the more the rust the more it'll cost to body work