Well, something like that. Whether it's 30 or 40 or 50 percent I don't know, but it's a significant percentage.
Yes, some completely foreign families come here on the DTV but I can't see them living here for 5 years. It's not a stable lifestyle. Besides, it's a new visa so let's see how long they last. For young families wanting to experience something new or going on a sabbatical for a bit of fun, sure for Russians and Ukrainains with an uncertain future it could be more long term but not for other westerners.
Different if you're married to a Thai and have a house and everything you can simply switch to another visa if the going gets tough on the DTV.
Vast majority, no. Maybe 50%. Thailand is the kind of country where most expats have an existing connection to the country...I can't imagine too many western families moving over here given how difficult it is to find work unless you're a teacher, the very small likelihood of attaining permanent residency or citizenship and always been seen as a tourist.
Most families coming on the DTV are probably only staying a year or two definitely not permanently.
99.9% certainly not. Many DTV holders have an existing connection to Thailand and are simply converting to the DTV for now as each entry is for twice as long as previous multiple entry visas. I'd say half of DTV holders have an existing connection with Thailand and thus a Thai bank account.