1. Varies by type and age of RV, where you live, etc. Many threads here findable via the search feature that will provide insight and companies.
2. Usually separate. Coach Net and Good Sam are the most widely used.
3. Yes, you can walk the top of a RV.
Vince and Susan
2011 Tiffin Phaeton 40QTH (Cummins ISC/Freightliner)
Flat towing a modified 2005 Jeep (Rubicon Wrangler)
Previously a 2002 Fleetwood Pace Arrow 37A and a 1995 Safari Trek 2830.