Hi and welcome. The things I usually look for in a storage place; fairly level, good drainage (gravel or paved - avoid grassy fields), the type of clientele (does it look like a junkyard?, this can bring rodents and bugs), security (fenced, gated), 24 hr access, easy of getting in and out, assigned spaces, spaces large enough to allow access to the RV while parked, ease of backing/parking the RV in your space. We were in a storage area when we owned a FW and the access gate wasn't far enough off the road and it was downright dangerous trying to open the gate with the tail of the FW hanging out on a busy road.
As far as covering, you'll get differing opinions. I've tried covers in the past and found them more work and risk than value. Tire covers, depends. If you use your RV enough the oils in the tires will keep them in good shape. If it's going to sit a while, especially in the sun, tire covers are a good idea. tires will age out on Rvs before they wear out and sitting and sun exposure are the worst culprits.