All liens against the property must be satisfied and cleared as part of the sale. This can mean all monies due are paid, or the lender agrees to other terms in order to call the loan satisfied.
Most people have loans against their houses. Such loans are called mortgages. Extremely few people can purchase a house without obtaining a mortgage. You sign a contract to sell a particular house....
Well this will depend on what kind of FHA program you are insured under for your mobile home. If it is a "Home Loan" under 203(b) program then only under certain circumstances will you be allowed...