Using Skyteam's tool, I've got my basic RTW itinerary right now as:
PIT-DTW-NRT-BKK (NW)
SIN-CDG-MUC (AF)
MUC-AMS-DTW-RDU (NW)
RDU-EWR-GCM (CO)
GCM-EWR-PIT (CO)

Unfortunately, I'm a bit of a newbie at planning RTW tickets, and though I've already spent lots of time reading (and re-reading!) these boards for information, I still have some questions that I'm hoping some of you can help me out with??

Basically I'm interested in paying for a business class skyteam RTW ticket.
1. only the 29k RTW has the business class option, right? the 26k only has economy?
2. if I get a business class Skyteam RTW, will I be able to get NW's "World Business" class? Or will I have to get a first class RTW ticket?
3. when using the Skyteam tool for BKK-SIN flights, I get the message: "This City Pair is served, but the timetable did not find any logical connections." Does anyone know what this means? Will I be able to book a Skyteam flight between these two airports? (and yes, I have tried different dates, but I still get the same message)
4. if there are no flights between BKK-SIN, let's say I decide to pay for my own trip (out-of-pocket, separate from my RTW ticket) for a one-way BKK-SIN ticket. Will the RTW ticket let me do this (i.e. arrive in BKK, but depart out of SIN)? Will the mileage between the two airports count against my total RTW mileage?
5. in previous posts, they listed the fare classes for _award_ RTW tickets - are these the same fare classes used for _paid_ RTW tickets too?
6. are there any benefits to booking paid RTW tickets with one carrier over another? For example, I have elite status with CO, but based on my RTW itinerary, I have a lot of NW flights, so would it be "better" or "easier" (in terms of ease of booking, finding availability/routings, etc) to book my RTW with NW even though I have elite status with CO?
7. in an earlier post which listed the rules/fares (circa 2005), it says that 2 international arrivals & 2 international departures were allowed for RTW tickets originating in the US (aka Area 1). I just looked on Skyteam's website today, and their terms & conditions are very sparse, and don't mention this point. Is this still the case for current RTW itineraries? (otherwise, my RDU-EWR-GCM-EWR-PIT segment would be invalid).

OK, so that's all the questions I have now, though I'm sure I'll have more as I get deeper into the booking process. =) Thanks in advance to anyone who can help shed some light for me! =)