Look up S39 Garage, they are in Bangna. I have had servicing and maintenance on a number of BMWs that are out of their BSI period done by S39. Very happy with their work and prices.
If your original country allows it, you can have both passports and retain citizenship of both countries. You can only use your original passport outside of Thailand.
Search for Interwood Timber Co.,Ltd. I buy most of my lumber from them. They have a Facebook page and website, you should be able to find white melamine boards from them. You will need to be able to communicate with them in Thai.