Does anyone know what RC coding the E sky helicopter uses?

The transmitter says: XTAL, FM_PPM, 4 CH, 72.810 MHz.

Does this mean it's:
Single conversion / Double Conversion)?
(+/-) FSK (frequency Shift Keying)

After reading a site about the workings of RC coding techniques (like PPM, PCM),
http://www.torreypinesgulls.org/Radios.htm

I've decided to use the Esky transmitter and a new 4 channel receiver to put into an EP aerobatic plane I just got off ebay.

But before I can get a 4 ch, 72MHz receiver I need to find out whether the esky uses:

1) single/double conversion
2) positive/negative FSK
3) whether a 5+ channel receiver is OK w/ a 4 ch transmitter (the above mentioned site has lead me to beleive so).

Thanks,

Daniel Korytina