I did a notarized translation before apply the visa (Portuguese to English). I paid about USD 15 per document. You have to find somebody that can do it from your language to English.
Last Wednesday I arrived in BKK from Bali, after staying in Thailand since October. I prepared some documents, like Bank statement, work contract... in case the IO would ask. 2 guys in front of me were asked many things like flight return, prove of accomodation... But when came my turn the IO just looked my Visa and stamped another 180 days. I think it depends. They may ask or not. It is better be prepared.
I plan go to Mukdahan/Savannakhet next year to renew my 180 days. I hope there will be okay too. In my opinion I think it's good stay few days in Laos for the visa run. In the past I usually went to Vientiane for visa runs.
Só fiz a declaração de residência porque a conta não estava no meu nome. Se você tem a conta no teu nome provavelmente não precisa de declaração. Sobre os extratos é bom ter um valor consideravel nos últimos meses, talvez eles examinem a movimentação bancária também (só no último mês tive o valor total requerido). Só precisei escrever o local que iria ficar (hotel, endereço, etc.) e o número e a data do voo, não precisei comprar a passagem antes.