Depends on location but mostly no problem, you will need residence certificate from immigration office, signed power attorney from seller with copy his ID card, and most important is original green book
Easy, go to pier near immigration office, someone will ask you what you need and arrange boat ... Boatman will care about everything, copies on thai side, copies on Myanmar side etc
36, yearly ... but as i mentioned above, it is travel insurance with unlimited cover, dentist to 333€ ... The insurance covers the costs of treatment, hospitalization, medicines, medical examinations, transportation back to the homeland, in case of sudden illness or injury, etc. in accordance with the insurance conditions.