As far as how much oil we need to know what year(s) they both are. The job can be done with common hand tools and a vice with the exception of a pair of snap ring pliers and a piece of PVC pipe to drive the new seals in. Other than that it should be a piece of cake as long as the seals aren't too stuck in the lower legs. An impact gun comes in handy for popping out the allen key bolts on the bottom too.
John
1985 Eddie Sanders ATC330r
1986 Monstecate
1984 ATC70 (awaiting 125cc transplant)
1984 ATC125M
1986 GSXR 750 - Keepin' it old school!
1999 Arctic Cat 500 4x4 plow machine
1999 Arctic Cat Thundercat 1000 (lake lizard)
1996 Arctic Cat Jag 440 L/C (ditch banger)