to elaborate on Pete's comment, since your initial stay was under 90 days you wouldn't file the 90 day report. Once you visit Thailand again, then the 90 days starts from that date.
Anonymous participant 134 yes I applied again the day after the cancel, and then it was approved. The first time took 21 calendar days until the decision. The second time was shorter than that
Pending approval just means it got past the pending document check stage. On my first application attempt, mine also went through the same stages and then it was cancelled.
I can only comment on the first paragraph. You don't need proof of flight. As for the accommodations, I booked a hotel first that is fully refundable and used that. After DTV is approved, you can change that hotel booking as you're not committed to it.