now the system is changing and I dont believe they allow new applications more than 60 days in advance. Besides, any further than that and the rules could easily change again.
needs to be booked on one ticket with luggage to be collected at final destination. anythiing requiring self checkin (ie change of airline in Bangkok wont work)
whatever works for you go for it. I figured 400baht was worth me taking the time to go and wait at MFA considering the difficulty to park there etc and then wait around. If you are in a hurry to get the paperwork certified then going to Bangkok may work best for you. Good luck!
You can get it translated at most translation agencies. But it still needs to go to MFA for certification afterward. I had this done in Jan 2016 - 1800baht total (400 translation, 400 for the translation sending it to MFA on my behalf, 1000 for the MFA stamp) - took about 3 weeks to come back. You can probably get the translation done in Chiang Mai but it will need to go tpo MFA in Bangkok for the stamp.