Looking to buy a zx5 with 115k miles for $3500. My research indicates these should be pretty reliable used cars.

No rust on the car, engine appears ok, but a little rusty.

On the inside, we noticed a couple unusual items..
1. The fabric on the ceiling and below the seats was "balled up" with lots of little *****. I have never seen this that I can recall, what might cause, should I be concerned?

2. The 2 brackets holding the seats to the floor are rusty (no black showing, just rust). Should I be concerned?

Any other suggestions on buying this focus?