you have to watch for tiny ports on the body. They regulate different things on the plan. That is why you should consult with an A&P mechanic to be sure not to cover any of those ports. Most average installer do not know where they are.
No vinyl does not alter the flight characteristics.
you cannot use regular vinyl on pressurized aircraft that fly above 13,000 ft. For high altitude you have to use special aircraft vinyl. That is the rule because of the expansion and contraction and air under the vinyl problems.
Rivets are a pain to deal with on small planes. However there is a small niche for this kind of work. You can put it anywhere on the plan.
The real problem is.. plans fly in the air and up there is plenty of dirt and oil vapor, paint chalking and other junk. You have to clean the plan very well.
Many plan owners are going back to paint. It simply last years longer.
Have a good time ...