The AB6 isn't great up front, but it's better than Economy. I'd say the seats are about the same size as you get on a North American narrow-body in F, although they are quite old. No PTV etc, and (at least for the planes i've been on) you can lift out the centre armrest/cocktail tray & end up with a sofa-type arrangement!

Can't comment on the food/drink as i've only used this on the short hops.

As for the hotel, if your room is ready then i've never had a problem getting access, but you could be out of luck. Jan-Mar is high season for Thailand. However, hotels are sooo cheap, you might be able to shop around & get a good price for a 2 night stay just to avoid the hassle. You're not going to get much sleep between CMB-BKK so this might be a good investment if you want to actually see some of Bangkok on your stay.