You'll find that most cars out there have very low miles and one owner- garage queens- OR have a bunch of owners as people purchased the car, realized it might not be the most reasonable and passed it on to the next. At least here in New England, the few that I looked at had quite a few owners- my theory being they probably sold them in the winter!

At any rate, I wouldn't worry about a car that has sat a little while, just make sure you look over the common problem areas (rust on the bottom of the doors, etc).

As mentioned, you can switch out the rear tires but then you loose one of the more endearing features of the car! Many a gentleman will be impressed when you start spouting things like "staggered" and "19's in the rear". It sounds like you'll be happy to just get in and drive so I wouldn't worry too much about modifications, these cars are pretty reliable on their own.