The convention seems to be 2.4Ghz for telemetry back the to base-station or radio display - and something lower in the UHF band like 433 or 900Mhz for actual control.
Mainly because Zigbee/802.15.4 radios are readily available in 2.4Ghz and 433Mhz goes a lot further (and through more things) by comparison at 1W.
[/sitting next to 3 hexacopters at the moment]
I only ask because most new 'brand name' (JR, Futaba, Airtronics, Robbe) tramsitters seem to be 2.4Ghz. I know FM radios are still available on 36 and 40 Mhz, among others, but I haven't seen many used for a while with new aircraft.
Control is real-time, just like any other flying model aircraft or multirotor. For flying at that altitude, I'd use FPV - meaning you'd fly using the camera image to pilot the copter viewed through a screen or even better, video goggles, as opposed to looking at the model from the ground.
Be aware though that at this altitude, you're often in controlled airspace, which is troublesome for model aircraft in most cases.