Yes, I saw officers asking elderly people to go to a different lane. But you should really ask for special assistance - someone will pick them up in a cart or even put in a wrap chair from the plane and take through immigration
There is no such thing. Flight prices are dynamic. Check them on Google flights. PS there are no flights to Pattaya, you fly to Bangkok and take a car/bus to Pattaya
I know someone who just went into a queue again and got to a different agent who didn’t ask her any outbound ticket at all. So many incompetent agents out there
it really depends on the agent and how experienced they are. Those working with the airlines for a while know that return ticket rule is not enforced by Thai immigration, while a new agent can just read off the list of requirements and is not familiar with different types of visas. It can also happen that one of their passenger was not permitted in Thailand by authorities and airline was fined and had to fly them back so now they are more cautious. As a rule, airlines are the ones checking all required documents including passport validity, visas, return tickets etc - before checkin