asked nothing it is crazy if you bring those documents to show at the airport even you have that visa already anyway in my case i reenterd thailand on dtv twice they asked nothing just gave me 180 stamp
i used to ride a motorbike to the chiang khong border it takes about 4 hours to the border so you can leave in the morning and come back in the late afternoon
this is thai! nobody knows what may happen. anyway if they really gonna tax my income from outside of thailand, i will stay less than 180 in thai. Vietnam and taiwan is good options to stay instead of thailand for a few months