A couple of questions for you:
1) Is the Conquest narrow banded?
2) Are the servo connector pins in the receiver sockets or on the servo lead?
3) Are we talking AM or FM

The reason I'm asking these questions is that I also have an AM Futaba Conquest four channel on Channel 48. Mine is a 1985 vintage that hasn't been narrow banded, so it's illegal to use per FCC rules. As for the receiver and servos, if it has the old style sockets on the receiver, new servos won't work without either getting an adapter or replacing the connectors on the servo leads, making it more cost effective to replace the receiver when relacing servos. If it's an AM system, you would be better off replacing the receiver anyway, as most of the better quality/higher channel count radios are either FM or FM/PCM.
Almost forgot your other question. The number of channels really is dependant on what you really want your radio to do. If you want separate servos in each wing, you might want them to be on separate channels rather than using a "Y". There are flaps, retracts stabilators, spoilers, bomb drops, smoke systems and who knows what all else. If you plan on any of these, you would be better off looking at the 7CAP or even the 9CAP Super 2. If you don't want to get that complex, stick with a 6EXA(or the latest version 6 channel), as you will still have some mixing capabilities, as well as Expo, EPAs and some of the other bells and whistles that are available.
Hope this helps