Done umpteen trips back and forth to UK but never had jetlag. I wear myself to a frazzle day I travel and get an evening flight, sleep a min of 8 hours whilst on board. When arrive I party as late as possible first night, NOT lay on the bed, but shower and get out. Then so tired sleep all night again and day 2 I am in Thailand time zone. The US may be different but also have UK friends who can't adjust as at the least sign of tiredness they go lay down irrespective of the clock
To the immigration office in the province ypu are staying in and registered your address (if your in hotel ask for copy of TM30 which they automatically fo fir you when you checked in)
yes your right BUT only need go to neighbouring country and I'd say less than a week from what i see daily, many in the group give details of where they went and how it went to.
I suggest you come with a travel cover to start, then ask around expats and talk to brokers. Medical insurance are annually so not sure suitable for you and much more expensive as they don't send you home for surgery but take care of you here, very different