a lot of questions....

I understand that the trial is for a few nations only...we will know more after the trial

Actually at the outbound process, security (which is in front of the immigration booths) is the bottleneck, the queues (even at the fast track) are on front of the security, hardly any wait at the immigration...therefore I agree that automatic doors at arrival would be more helpful, but I have not seen any, which also places a stamp into the passport...

here a link to an article with more info:
Thailand's immigration introduces automated passport control at Suvarnabhumi Airport - TravelDailyNews Asia & Pacific