new *potential* owner from nj with questions

Been shopping around for awhile and have finally settled on getting a couple 400ex's for my buddies and i to play with.

i'm going to check out two next week; both 07's, one red, one black. the guy apparently has had a baby and the they haven't been ridden in "18 months."

i'm using the search function to look around and try to find some other answers as well. but still have a couple if anyone can help out....

if i'm looking at a couple quads that haven't been ridden in this along, what problems should i be prepared to face? they will obviously need new batteries, and im certain he never put stabilizer in before he stopped using them. so at the least the tank and fuel lines could be emptied and cleaned.

with them sitting that long is there a good chance i'll have some carb problems? anything else i should look into?

thanks for any help offered!