It's a 6 month multi entry tourist visa. You will still only receive 60 day stamps that can be extended to 90 days and require leaving the country atleast 1 time to use the full 6 months.
I used a thai bank account. The only additional questions where proof of where those funds came from outside thailand. I had to show transfers from us accounts etc to prove I wasn't earning money in thailand
They want to know how you make money. How did you get the 500k to start with? How do you plan to earn money going forward it's that simple. Seems like a reasonable question. If your answer is I don't have a plan and I only have 500k baht they will most likely denie you. They assume that you'll end up working illegally in thailand if you don't have a previous source of income to fall back on.
Careful with leasing land. Thai Supreme Court just ruled on some 30 year lease renewals for land in phuket. Even though the contracts had agreements for renewals they aren't enforceable and its upto the owner if they want to let you renew, which given the skyrocketing land prices in phuket they did not and the land was forfeit. So land lease renewals even with agreed on terms aren't safe past the first 30 years.
I attend the wall chiang mai and they provided everything I needed for my visa in a nice packet for immigration including copies of all licensing, course schedule etc. Highly recommend.