you have 90 days to enter Thailand from date of issue. You will then have 60 days validity upon entry to Thailand. So, you could enter 2 and a half months after tourist visa has been issued to you, upon entry to Thailand you will be stamped in for 60 days still.
unless it's changed then you can't switch in country on this visa. OP's best bet is to start looking on jobsdb and LinkedIn and see what's available. There are still multinational companies hiring non-Thais and relocating them but there are fewer of these jobs now compared to 12 months ago.