Get a tall A-frame type ladder (if you don't already have one), and take your time putting the cover on... on a windless day!! If it is windy you will probably need someone to help you. Or just wait for a calmer day, lol.
Yes, the cover will wear out over a few years. The more expensive the cover, the longer it will last (usually).
Secure ALL the available spots to put rope / bungee cords. Most times when people talk about covers causing wear due to wind it is because they skimp on securing the cover completely, so parts of it will flap in the wind.
You only have to deal with the cover twice a year (fall and spring), so it really is no big deal. When you put the cover away for the summer make sure it is dry and folded neatly (or, as best as you can). Try to keep mice out of it!
Actually, I just use a standard tarp to cover my 21 foot TT. It is something like a 15ft by 30ft, so it can be tricky to deal with. I am just too cheap to spring for a nice TT cover, as camping friends remind me - lol! If I had a larger camper I think I would buy a nice fitted cover.
The absolute best thing is to have a large enough garage / shed to park your camper, but a cover helps to keep the camper clean over the winter.