Just carry more funds arounf 40k this time and say them last time i put my money in travel card but immigration officer ask me to show cash in hand , they will check ur all documents and will ask u thats it you can entry no worry
You can search on craiglist thailand plenty of teaching jobs for native english speakers , as you are coming for 10 days u can find it easily in bangkok once u selected school will provide u business visa with work permit