the accommodation shouldn't be an issue if you go for one with a booking you can cancel, booking.com usually has a few. In terms of the flight out, I found one from Krabi to Kuala Lumpur for about 25 dollars, which is only about 10 bucks more than the onward ticket "flights." I know what you mean though, it is a faff for just those 30 days. I'm waiting on a work visa to get sorted so it was worth it in my case (although still a pain in the arse) but I understand your reservations!
you're welcome! Yeah it's a bit excessive, although I see it as 90 days total because the visa is 60 days, then you can extend in Thailand by another 30 days. If you want 60 days total, just fly in without a visa for your first 30 and extend in-country - it's 1900thb and you only need a photo, photocopy of your passport, and photocopy of the page with your entry stamp.
And this should go without saying, but all the docs need to have your first and last name visible somewhere. It was more frustrating that it needed to be (no surprises there) but ultimately straightforward if you're properly prepared
Just did it this week. You'll need 6 months of bank statements with $600USD in the account. The website states 20,000thb, I had 20,000THB in the account, they said it wasn't enough and I should have more. You need flight itineraries for your flights both in and out of Thailand (actual flights, not one of those onward ticket "confirmations"), proof of accommodation reservation for your whole time in the country (obviously some bookings let you cancel for free and that's fine if you just need something to keep them happy, but beware that if you haven't yet paid for the accom yet, they may ask for more in your account, especially if the accom cost isn't covered by the amount in your bank account), you need 1 passport photo and a photocopy of your passport page. There's a copy shop next to the Mercure hotel nearby. It costs $40USD, but you need to pay in USD as they won't accept Baht or Dong. They've got the form you need there. I turned up an hour before opening (no booking required) and it was unnecessary, 10 mins before should be fine. The earlier the better, because most people aren't aware of everything they need and you'll end up stuck behind people who are unprepared. Or people who are prepared but get asked to jump through hoops they didn't know about. It can take 1-3 working days, mine took 2. Also, double check on Thai holidays as I rocked up on Friday and it was King Bhumibol Memorial Day so they were closed. My main advice is give yourself enough time.
the Bangkok Bank up in Pai does it over the counter for Visa Debit no issues - all you need is a passport and to be withdrawing a minimum of 10k. The only caveat is they won't do withdrawals for foreigners in the mornings during high season. I assume it varies branch to branch.
If you take your passport to a Thai bank and are planning to withdraw over 10,000THB, they should do you a cash advance with your overseas bank card at no extra cost. Can't speak for your exchange rate or bank specific fees, personally I use a Wise card that's fee free.