@Ruairidh *****************

no. If you want to work with Thai businesses you would have to give up the DTV and change to a Non-B visa with a work permit. Either you work i. Thailand for a Thai entity or you work remotely for a non-thai entity located outside of Thailand. There is no visa that allows you to do both

It's a simple process. You visit immigration and fill out a 90 day report form

Nothing happens as you won't be issued a 2nd visa in that way. You need to attend immigration and apply to change your visa from one type to the other. I assume the BOI can advise you on how to do this since they are the ones that issue LTR visas

Nothing happens to it. He should just carry both passports

Their website quotes 7 working days BUT it also says it only processes applications from those with a right of residence in Hong Kong. Assuming you do and they process your application you need to remain there until the process completes

I don't think you can get the ID card unless you are married to a Thai or have purchased a condo as you first need to get a yellow house book but the requirements for obtaining the house book vary by area so best to ask your local office. On a tourist visa like the DTV I can't see another way for you. A Thai driving licence is accepted as ID virtually everywhere

@Ricky *******

maybe. A visa is not a guarantee but it helps

If you are doing this every year then your chances of being denied entry increase. It's not a good plan for living inside Thailand 6 months of every year

@Ricky *******

you still need to border bounce, it gets you stamped in for 60 days same as visa exempt or a tourist visa.

@Neil *******

not true