You are required to pay PMI (mortgage insurance) if you don't have 20% down; but he doesn't have to worry about that.
Generally speaking, I would make sure you have an inspection contingency and a financing contingency on the offer. These alone can help you get out of the deal if something comes up. If you have a good buyer's agent they should help you with the offer and what sorts of contingencies should go into it.
Since you are able to put 20% down, you can go with a standard 15, 20, or 30 year fixed mortgage. Your mileage may vary but I prefer to lend from whoever is going to own the loan (i.e. even though I bank at a local credit union, I didn't get my mortgage through them because they just resell it, and it turns out they were reselling mortgages to a bank that failed...). I have had my last three mortgages through Wells Fargo and everything has been fine. The big banks have mortgage departments and mortgage pros who will help you negotiate all the paperwork, closing costs, etc. For the three houses I have purchased, my only expense other than the actual house was the inspection and appraisal fees. Everything else was always covered by the seller as part of the deal - but that's the Midwest for you right now.
Escrow for taxes and insurance makes it easier, but you are basically giving the bank your money and they get to collect interest on it instead of you. Since interest rates are sucky right now that's not too big of a deal, but still, you are giving money away. Unfortunately, MOST lenders require them now.