rust challenge 101

i have my 1994 xj and i was wondering what the rest of you xj owners do to repair rust. currently my rocker pannels are non exhistant which i am going to replace with 2x6 square tube in the summer. what about floor rust? i want to linex the floor one day but not if it has rust on it. i made a sandwich over the muffler for a rust hole in my g/f's xj with sheet metal, sealant and rivits. unfortunatly i cannot weld at the moment but once i am able to is it just as easy as cut and paste? should i start worring about structural integrity? especially when i flex off road? and finally what about the roof. i have a rust spot thats gettign worse on the roof directly behind the drivers side roof rack rail. it will leak eventually. should i cut and fiber glass and pay lots of money to have it painted?