1. You should need a high number of channels or maybe a multiplexer only if you plan functions beyond the routine propulsion controls (animatronics, firing unit, lights, smoke, sound, etc.).
A very experienced modeler on this forum is Vince Abbott who employed a Robbe-Futaba FC16 with added on switches. You might try to contact him for an opinion about suitability and set up. Or contact Lee Sellars and others here, they are well familiar with these too.
2. I initially tried to find a Robbe-Futaba FC-14 or FC-16 set for my Tiger I in the USA, but had no luck; I could find them in the UK and other countries but none in US legal frequencies. The frequencies in the USA per FCC for ground vehicles were: 27 and 75 MHz, or 50 MHz but ONLY if you hold a HAM Radio Licence. Note 72 MHz is reserved only for aircraft.
3. It is possible to buy components to covert frequencies of some R/C control units (72 to 75 for example), but you need to check with the factory distributor of the R/C unit in your country for compatibility and availability info.
4. Some newer developments involve 2.4 GHz digital RC controllers that can be used for either air or surface. A number of older sets can be converted to 2.4 GHz (I did this with my Futaba 14MZ 72MHz set).
5. You might prefer to buy a new 2.4 GHz unit - especially if you wish to operate air and surface craft with the same controller, or if you prefer some of the new features (no worries about others on the frequency, etc,). Note this newest 2.4 GHz technology is prompting a number of older 27/50.72/75 sets to come available for sale discounted or used at modest prices.
6. Also, among the neat aspects of the latest Armortek PCB electronics are their providing a 4.8/5 volt DC output (converted down from the main operating batteries), and so there is no longer a need for the heretofore separate 4.8v Receiver Battery and Charger.
Did not intend to write a book on this. Best of luck with it
