Hoping one can help me with experience on AirAsia. Personally, I try to avoid the ULCCs - I have tended to see the upfront prices + add-ons like baggage, seats, etc.. usually be not much less than full service carriers, when all is said and done. But trying to get from CNX-HHQ (Hua Hin), and somehow, AirAsia flies this - as far as I can tell the only flight into HHQ at all, and considering it because it avoids flying to BKK, then having to do a ~3 hours from there. Flight isn't even that cheap - at least on the day we need to go - roughly about the same as TG into BKK. But convenience a big factor here...especially since we're traveling with our 8 and 5 yo daughters, so avoiding a 3 hour drive to HHQ (plus to a lesser extent, the additional cost of transportation to Hua Hin), tips the scales to the flight that will get us right there.

So the questions I have:
- my understanding is our bag allowance should be combined - so if we buy 20kg of luggage each (or more likely the 'value pack' or whatever that is), we should have 80 kg total, regardless of how this is divided (assuming it doesn't go over AirAsia max. bag specs). For example, if we have 4 bags, 2 that are 23kg, the other 2 are 16kg, we should not need to pay for extra. Is this correct?
- Is the standard carry-on allowance (7kg) enforced by weight - and can there be more than one bag that add up to the limit, or is that limited to a single bag (either roller board or backpack). Seeing some threads on places like Reddit that seem to suggest they do tend to check pretty aggressively at KUL, but mostly not at other stations, but don't know if that is dated. Also have heard that a laptop bag can be brought on in addition to the stated allowance. Assuming we're not bringing large bags - we might have a standard carry on size bag, and then backpack and laptop, is luggage likely to be weighed at a station like CNX? Understand that if it is weighed, they are probably pretty strict on charging for any little thing above 7kg exactly. Any idea how much more this is to book at the airport vs. at time of buying the ticket (for the record, the charge for an extra 7kg carry on at booking seems to be ~$13 USD
- Any idea, should we need to add extra checked luggage, if there is a price difference to do in advance, but after ticketing, vs. at time of purchasing ticket. Also, how much more to do at the airport vs. at least 4 hours in advance?
- In looking at seats, I assume the price difference for 'hot seats' vs. the rows just behind that vs. the rows at the back of the flight are just based on how close/far they are from the front of the plane, correct? Or are there seat pitch differences, for example, rows 1 - X have extra legroom compared to those in the very back.
- Any other 'gotcha's' I should look out for?

Appreciate any advice.