yes cost is 1,900THB BKK doesn't care when you extend it, you can literally arrive at 8am on a Monday go to Immigration on the same day and get the extension...this is only possible if its not a holiday and the immigration office is open...Chiang Mai might not be so liberal, so have someone call or stop in...
you're correct it is the yellow book...they issued the Yellow book at the Ampur to go to me and the blue book to stay with the owner... easy process took 2 weeks in the pre-covid world
that’s what I did I was added as a tenant on a residence for the tambien and received a pink card…easy process just took about 2 weeks if I remember correctly