Your employer is the one that applies for your work permit and Non-B visa. You can't get them yourself then look for a job. That isn't how it works. If you quit your job, your work permit is cancelled as well as your visa.
maybe it was just the wording of your comment that made it sound like you didn't realise it was a multiple entry visa, so he can use it repeatedly, not just once, to enter before the September expiration date.
you must not have noticed that the OP posted a multiple entry tourist visa, which means it can be repeatedly used as many times as he wants up until the September expiration date to enter for 60 days each time.
15k a month obviously. No way can you run multiple ACs and keep it under 1.5k a month. I average 9000k a month for 2 ACs turned on maybe half of each day, set at 26C (79 F), paying government utility rates (not marked up like some condos.) 15k is certainly plausible for a house.
Why would you visit Thailand for the first time and skip Bangkok? Would you visit the UK for the first time and skip London? Or France and skip Paris? People telling you to skip it are people who live here or been here multiple times and know what towns they prefer. Much like many Brits don't like living in London or many Italians don't like living in Rome. But for visitors, it's completely different.
You can only extend one time for 30 days. You can exit and re-enter for another 30 days visa exempt entry, and extend it again for another 30 days. If you do this repeatedly, immigration may stop you as you won't seem like a genuine tourist. You can also apply at the Thai consulate in another country for a 60 day tourist visa, which can also be extended once for 30 more days.
if you are in Thailand longer than 3 months, the IDP isn't accepted as you are supposed to get a local license. That's all people are referring to. Valid real IDPs are accepted together with the home country license. IDPs can't be used alone without your home country's license.