I just got a 2011 KK myself. Could be that whomever owned it didn't wash it and left the road salt run it's course. Road salt eventually killed all my vehicles. It's a lot of work just to keep it under control. Just one winter in the salt can do a lot of damage. All the things you mentioned are very common areas for rust to start. Door hinges have sharper edges where the paint is not so thick and rust starts to form there. Plus people are not so good at cleaning them since it's a pain. Wiper arms are a common area for rust. I don't think they are painted very well plus they get a constant spray of salt and uv from the sun. On my older vehicles I have resorted to painting the arms every year. Maybe I should get some better paint now that I think about it. The exhaust sounds normal. I bought my 2011 with only 10k miles on it and it had only seen one winter in the salt The entire exhaust assembly was coated in surface rust. My rear axle and other suspension parts had some some patches of rust also and this is coming from a person that was diligent about washing it top to bottom. It's been my experience that undercarriage parts especially are not painted painted very well. They get a heavy coating of salt and are being constantly battered by debris. Unfortunately rust can start in just one day if the metal becomes exposed. It's not uncommon to replace the exhaust 2 or 3 times in the life of a vehicle around here due to complete failure from rust. Depends on the quality of the parts bought.
Battery terminals definitely will get corroded. I clean mine probably once a year. Use a wire brush to take off the corrosion. Next apply a baking soda and water solution to neutralize the remaining corrosion. Rinse and wipe that off. Next use a handy battery post cleaner to freshen up all the connections. Don't use the same wire brush you just cleaned the corrosion off with. Lastly coat all metal surface areas with dielectric grease. Coat everything right up to the insulation on the battery cables. The cables can begin to rust internally where you can't see it if you don't do this.
Yours has 50k so you certainly can see rust problems in all the areas you mentioned. This goes for any vehicle. As for the wind noise I noticed the same thing when I first drove mine. It's most noticeable around the windshield. Not sure about your rattling sound. Sounds like something is happen there.
As for the skipping at highway speeds I'm not sure without knowing more information. You may need to do some tune up maintenance. Hopefully it's something simple.
When I see the car was only in snow for 1 season, and all that rust, I was getting concerned.
The dealer backs this 100% for 30 days. Plus I think Jeep covers the powertrain for 100k ( which I need to transfer to me ).
If I see flaking rust on the exhaust, should I ask the dealer to repair/replace the piping or is that not their responsibility? Can a few flakes really be an issue?
Sorry you have to deal with this. Once the rust starts the only way to get rid of it is to remove it completely down to clean metal or replace the metal otherwise it keeps getting worse. That's why it's called car cancer. It's a constant battle where I'm at. Flaking rust on the exhaust is not a problem until you end up with a hole, then replace the parts. If you have the owners manual and disk the warranty information should be on there or look it up on the internet. I don't remember exactly, but the exhaust warranty is probably short, maybe a year. I'm pretty sure the warranty does not cover any rust damage due to salt among other things. Best to look up the warranty and ask the dealership if anything might be warrantied. It doesn't hurt to ask.
Check the warranty. There is a corrosion warranty, I just don't remember how long.
The sheet metal corrosion warranty is 3 years and painted metal panels(ones you see walking around the vehicle) is 5 years 100,000k.
Your warranties donít cover damage caused by
environmental factors such as airborne fallout, bird
droppings, insect damage, chemicals, tree sap,salt,
ocean spray, acid rain, and road hazards. Nor do your
warranties cover damage caused by hailstorms,
windstorms, tornadoes, sandstorms, lightning, floods,
Your warranties do not cover conditions resulting
from anything impacting the vehicle. This includes
cracks and chips in glass, scratches and chips in
painted surfaces, or damage from collision.
'02 Liberty sitting on 35" tires,HP44,RockJock60,and AtlasII t-case