In a city of 11+ million people where do you mean "in Bangkok"?
Exchange places outside of the airport are mostly the same. Unless you're changing a huge sums in which case you won't be using a "street" exchange it doesn't matter.
B) you asked the same/similar question back in November - it hasn't changed.
I suggest you look at the Thai embassy for the country you reside in to get your specific answer - a little bit of homework will save you waiting for replies on here.
without being rude, age will be against you finding work in Thailand. Not impossible but it's quite an ageist society when it comes to employment. Over 40 and you'll struggle to compete.