Insurance is going to depend on who, what and where you want to cover.
We have National General which used to be GMAC. In the 13 years we have had it we haven't had any large increases in payments.
Recreational Vehicle Insurance Quotes | RV and Motor Home Insurance Coverage & Rates| National General Insurance
As far as extended warranties be sure to read the fine print since they are in the business to make money. The first year or two of ownership of a new coach will normally be covered by the manufacturers warranty so you don't need to buy a warranty from the dealer. Shop around and read the reviews from other customers and as I said "READ THE FINE PRINT". They will use every excuse to refuse paying a claim they can.