MMR, TDAP at the very least for the safety of you and others would be highly recommended. Hepatitis is also smart. As far as travel based recommendations, typhoid would be at the top of the list.
is plenty, that's enough for 6x 4k videos at once, or 60x 1080p videos at once. Most people grossly over estimates their bandwidth needs. If you want faster go faster, but a usually person would never feel the difference between 300mbps and 2gbs.
if you have a second residence in isan and want a local car there, then you just need to meet the local requirements for a resident certificate (you need to check with immigration as each office has different requirements) then you are okay.
I would not recommending using resident certificate from a different province from where the car will mainly be, that might turn out to be more headache... Especially considering if you end up with a red plate.
not trying to confuse it. If he wants to buy the car, buy the car, drive it back to where ever their home is and get a resident certificate and get a plate for the province he actually lives in. Not a good idea to get a plate from from a different province through some trickery.
You don't need a resident certificate to buy a car, you need one to transfer the name in the book.
Your resident certificate should come from the province you will license the car. An immigration office will not give you a resident certificate from another province.