TM30 is a report made by the property to immigration where you're staying in Thailand.
Then you need to do a 90 day report to immigration if you've stayed in Thailand without leaving for 90 days. It's basically and update so they know where you are. Very simple
where did you hear this from??? Hahaha not true at this time.
No need to show bank statements every year or upon re-entry (assuming not using an extension because that is unknown and might vary between immigration offices)
Just do a border run. It's easy and you don't have to do any paperwork or anything, just show your DTV letter. When you return you'll get another 180 day stamp.
Incorrect on the other point. You can come and go as often as you wish during thr 5 years. Each time you enter you will get a 180 stamp. If you wish to extend that you can extend each time (not just once during 5 years).
But if you do what you mentioned for avoiding 90 day reports then there wouldn't be an opportunity for an extension because you would get new 180 day entry stamps each time.
With this visa, it might be possible to squeeze almost 6 years out of it by the way. Enter once right before the 5 years is over. Then extend.