2004 Honda Civic rusted oil pan?

Hi, I hope you can help me because I know a woman who literally knows nothing about cars other than how to drive them (and even then I can only drive an automatic!)
Took my car in to the dealer for an oil change and 70,000 mile service. It's an '04 Civic LE, leased it for 3 years then bought out the lease. I've never taken it to anyone else but the dealer for service, have never missed a service, I get the oil changed every 3,500 miles and I take very good care of it. It's a 5-year-old car with just about 71,000 miles on it, but I don't drive it as much as I used to. In the last 2 years I've had a job change and so in 2008 I only put about 9,000 miles on the car and this year I've put less than 5,000 miles on it.

This morning the kid at the dealer told me that the guy doing my oil change told him I had a rusted oil pan, which the kid mentioned is a little weird for a 5-year-old car. That immediately got me thinking why it would be rusted.

He then told me that I should really get it taken care of asap because if anything heavy falls on my car (like heavy snow, with winter approaching), it's going to completely go.

I told him not to do the work and drove the car home so I could do some research. The way they presented it, it sounds like my oil pan doesn't just have a little rust spot, but it's completely rusted. What would cause that to happen in a 5-year old, well maintained car. (The dealer has done ALL my oil changes and all my maintenance, so one would assume they're using the correct type of oil, etc).

*unrelated to oil, they also told me I have a radiator leak that needs to be fixed. I obviously don't want to let this go, but I'm skeptical that the service department might experiencing a slow work period and trying to take advantage of an unsuspecting woman. But would a radiator leak affect air conditioning peformance? I very rarely use the ac in my car, in fact, I'd say hardly ever, and yet two years ago it started blowing mostly warm air. I thought I needed to have it recharged and didn't bother paying for that because I so rarely use it, so I just never turned it on for the past two years - but now I'm wondering if it started blowing warm air due to a problem with the radiator.