If you have the money your easiest option is the Thai Privilege visa. There's also the DTV but that is 180 days at a time and you can only extend once before you have to leave and return. You won't get 5 years out of an ED visa
Pending approval means just that. It generally means it's waiting for someone more senior to sign it off. They may come back with other questions or they may not
I'd suggest that the only people who have been able to do this were not actually on a visa at all but on an extension of stay (which often gets wrongly called a visa)
It looks like you have a multi entry tourist visa so you have no option but wait until it reaches its valid until date. If you had a single entry tourist visa you could just enter Thailand on it and leave again then it's no longer valid, but yours allows you to come and go as much as you want for 6 months. You can't cancel a visa but you can continue to use this visa until it expires. You also can't hold 2 visas at the same time
One point on the 800k baht, if you're planning getting a 12 month extension on your 90 day visa the 800k needs to be in your account for 2 full calendar months before you apply for the extension
I suspect you need to show how you will sustain yourself, even though you are not working show how you will obtain money but leave out the gambling if you try again