There's a ridiculous amount of disinformation in this thread about tax and banking. If you can't figure out something at home or in Thailand, try to open an account at an offshore bank (e.g. Xapo Bank) or an onshore bank in a more lax jurisdiction, Georgia (the country) is popular at the moment.
My passport also expires in 2028. My DTV runs until 2030. The advice I have seen is to carry both passports with you + DTV print out at the border for the remainder of the DTV and the immigration officer will stamp your new passport.
Yes, your landlord is meant to file the TM30 every time you reenter the country. I'm not sure there'll be any hard consequences for not doing so. But if you need the TM30, e.g. for a certificate of residence to buy a car, get a driving license, etc. or a visa extension, you won't be able to use your previous one.
I put "HMPO" on my application, straight from the authority field on my passport and was accepted. For my wife's application I just put U.K., hers was also accepted. But I've also seen both ways get rejected on here so really it's a toss up.
I would think it would be fine to submit kitas, accomodation etc. If they have doubts they might ask for a picture of each page of your passport to check there are no new stamps for other countries.