It sounds like you are not using a Real Estate Agent or dealer. This is fine, but there is a reason that they have jobs, they know how to do all of this!
Our suggestion is to call a local title company, like First American Title, or Fidelity National Title. Ask for a the name of their escrow officer who handles the most mobile home escrows.
Once you find out who this is, have them tell you how much and what would be included in their escrow service.
You will need to pay close attention to paying off the old loan, paying the taxes, and especially transfering the title from the old owner to the new owner. If any of this is messed up you will regret it.
Start calling your local title companies, and your local Real Estate offices for the recommended Escrow officers handling mobile homes.