Your livability experiences (comfort, etc.) seem typical for this size car, though the details are likely to vary from model to model. Overall the Fit is considered reliable and friends who own them are satisfied, but they aren’t luxury cars and they burn less gas. Different models of tires vary in harshness and noise transmission, look at the Consumer Reports ratings.
The lower engine cover is there for a purpose - to reduce drag, possibly improve cooling by directing airflow to the proper places, and it protects from dust and splashes. Removing it might cause warranty problems, maybe… The screws and/or plastic pop rivets that hold them on frequently aren’t replaced properly or go missing, so have someone check and replace. Damage to the cover or its fastening points can be repaired.
As for hanging up on parking obstacles, I carry a thin sheet of stiff material (mine is corrugated polypropylene from a campaign sign, but cardboard works too) in the trunk to insert as a slip sheet before backing off an overridden curb - this prevented a lot of damage to a Jetta whose bumper easily was hooked and pulled off.
You might compare experiences with other Fit owners. Since new our 2006 Civic often fogs the windshield when the AC isn’t on, or when not in defrost mode (which in ours turns on the AC) and our other cars (Outback, Prius) do this to some extent.
A practice that might help a bit is to turn off the AC a few minutes before parking. This gives the condenser (the part that chills the air and upon which water condenses) a chance to dry, reducing the chance of it saturating the first blast of air the interior receives at the next start, and also can reduce mildew buildup and nasty AC smells.