Print everything. From the June 1st it's not a pre approval process but a pre registration process so it's not actually easier and you will have to present printed documents at check in and arrival.
yes. I actually came back two weeks ago from the UK. Still had to provide printed copies to check in and and at BKK. The Thai pass is redundant now and I can't see it lasting much longer.
they give them to you on the aircraft before you land. Just fill it in and have it completed to hand to immigration. They put a part of it in your passport. Don't ever lose it before you leave the country.