So I'm fairly new to watching Thai dramas and for the first time I'm watching one that's currently airing... I just wanted to clarify something.

They only air one episode a week, correct?

It's depends on which drama/channel its in. Some drama aired once a week but some have twice a week or more. You can check the aired time in their respective link drama profile. Stated below their cover photo. :) 
Hi, I'm not sure if your questions have been answered.

For dramas that air on national networks (Channel 3, 5, 7, 9 or Mcot - but Channel 9 Mcot is becoming a cable network channel) (a.k.a. "lakorns"), they have 2 kinds of dramas: 

1. Weekday dramas that air around dinner time, a.k.a "Evening Lakorns"
They air on weekdays (either 4 or 5 days a week, sometimes they don't air on Fridays) around 6 or 7 o'clock in the evening for only 30-60 minutes before the 8 o'clock news. I can't think of a drama in this time slot right now, but sometimes they air dubbed Korean/Chinese dramas at this time. 

2. Dramas that air at night, a.k.a. "After News Lakorns"
They air 2 or 3 days at a time like this: Monday-Tuesday (http://mydramalist.com/13865-kleun-cheewit), Wednesday-Thursday (http://mydramalist.com/16323-padiwaradda), Friday-Saturday-Sunday (http://mydramalist.com/9853-game-rai-game-rak). The time is after daily news finish airing at around 8.45 PM and they run for almost two hours (until around 10.30 PM). They're the most popular form of lakorns. When they finish airing, some networks/channels show their re-runs during the day but at least a month after they finish airing (and housewives watch these re-runs). 

For dramas that air on cable networks (GMM, One, GDH, Channel 8, etc.) (a.k.a. "series"), they don't really have a format for airing but mostly have this common point:

1. They air very late at night. Sometimes they air at 10 PM (http://mydramalist.com/16667-sotus-the-series) and sometimes they air at 11 PM, and they show re-runs right away after the original run is finished, and their re-runs are usually online, on Line TV or other mobile apps.

2. They air only once a week. It can be on any day of the week. It's up to them. Hormones (http://mydramalist.com/10032-hormones) aired every Saturday, and Ugly Duckling (http://mydramalist.com/13254-ugly-duckling-series-...) was aired on Sundays.
Thank you so much for sharing so many useful information, Zig! Just adding that OneHD or One31 (I'm not sure what's the right name), despite being a cable network, airs lakorns on Monday-Tuesday and Wednesday-Thursday too, but I don't know if it's at the same time as national networks.
anna -- We just call that channel "One". The number you press on TV remote controller is "31" so sometimes you see One 31. HD is just to indicate that it's in High Definition. (I'm guessing they have another TV channel that's not HD, but who knows, I'm not a fan of cable networks.) And yes, they probably air stuff in a 2 days/week format as well. I'm really just a national network fan because they air at the best time. When I finish school or work, I come back home, have dinner, take a shower, then it would be time for lakorns to air. I watch them. Cable network series air too late. I'm too old to stay up with those kids. Or maybe I'm just old at heart. I'm still a university student LOL.