To answer your questions:

1) Yes, all arriving passengers from the five international concourses (C through G) all come to the same terminal building at BKK. So do domestic pax, who have a separate "inside Thailand" area. There are, however, two exits from the "border of Thailand" customs zone: exits B and C. Although the customs zone is one big area and you can move freely inside it, the design guides pax who collect bags from belts 7-16 to Exit B and from belts 17-23 to Exit C. If you and your friends come out through different exits, it may be difficult to find one another because, once out of the customs zone and through the small roped-off arrivals area, the crowds are no different from those at Don Muang. For possible solution, see below.

2) Basically, yes. The flow is from all concourses to the area where the monkey guardians are, then from top to bottom. Everything is on the same level unlike, say, Incheon or the old Don Muang.

3) Yes. Customs is not before the baggage belts. Immigration is before the belts, customs after. The little symbols on the map are mislabeled. The little orange one with the guy in uniform holding up a paper is supposed to be immigration, not customs. The little orange one with the guy in uniform going through a suitcase is customs, not shops/restaurants.

4) It's not. Again, the symbols are mislabeled. The little box with the line between two planes is supposed to indicate transit desks/points, not passport control (immigration).

5) There are AoT official limo counters inside the customs zone, before the customs checkpoint. I've never done it myself, but I believe that if you get AoT limo service, the drivers or their helpers go to the belts with you and help you collect your baggage (read: help you drive the inoperable baggage trolleys). There are also Forex booths just inside the customs zone, immediately after you clear immigration. Both limo counters and Forex booths are also available after you clear customs, but the crowds and touts make that area a zoo, so I'd suggest using those inside the customs area. (For that and another reason, see below.) I'm not sure about ATMs.

6) SaigonCyclo has the correct pronounciation: Soo-wan-na-poom. Suvarna means "golden," bhum means "land." Has a nicer ring than "Cobra Swamp."

Yes, the map is very confusing. Mostly because the symbols are mislabeled.

Because BKK can be such a mess after you get out of customs and find yourself right in the middle of the meeters-and-greeters crowds (and taxi touts) in an area far too small for its intended use, I would suggest that if at all possible, whichever of you arrives first clear immigration and collect your baggage but wait in the relatively quiet and spacious baggage hall before clearing customs. You can check the arrivals boards to see where your friend's flight will arrive from, then meet him at the appropriate baggage belt. At that point, arrange for your limo driver and after the last of you arrive, go through customs together. This will keep you out of the crowds (maybe I'm making it sound worse than it is), make meeting up far easier, and solve the problem of possibly passing through different exit points. You should be able to hang out in the baggage-claim hall for a decent amount of time without a problem.

You can find more information about Suvarnabhumi in the Thailand forum here on FT. A search for my name will turn up several threads with extensive descriptions.

Speaking of the Thailand forum, how about getting this thread moved over there?