Should take all the photo copied pages with you having have them copied elsewhere, likewise fill the application in at home before going. I think some immigration people get a bit hacked off waiting for farang to fill out forms and get photo copies there, holding other people up.
Border runs are currently history even if the boarders were open. If you crossed a border a Thai pass would need doing and PCR tests and everything else that goes with it. It would be the same as any visitor coming to Thailand.
Go to immigration taking a passport photo and proof of where you live with you. A letter of residence is 300b and you usually have to come back to collect in 1 hour.