A close friend's mom passed away right after she got off a plan from the US. The people at the airport handled everything. Body to hospital, all the necessary paperwork, transfer the body to Chiang Mai. My wife and I found a temple for them and everything was accomplished for right around 65000 baht. There are companies that will handle all for you. The comment about not staying at the Wat overnight is a good one. Also, if you don't have a lot of friends coming don't get a waiting room. Just go from transport van to the crematorium.