2-) what transmitter and receiver I should use
That depends on the distances involved.
For UHF devices 433Mhz to 915Mhz normally, there are very often legal restrictions on duty cycle (how much time the transmitter may be on) of 1% or 10%, which may not be suitable for responsive RC type applications.
There may be exceptions to these UHF rules specifically for RC model type use that allow continuous (100% duty cycle) use but in the UK for instance you are then limited to a signal bandwidth of 25khz. HC12s are popular in the Arduino world, but there is no mention in the datasheet I can find of the bandwidth or deviations used, so the device might not be legal to use.
UHF LoRa devices can operate at 20khz bandwidth so in the UK at least, can be operated at 100% duty cycle but at that bandwidth the maximum data rate is circa 1kbps, probably not enough for RC applications.
Things are much clearer for 2.4Ghz operation, its basically a worldwide frequency allocation and few if any duty cycle restrictions. If distances are short, less than a couple of hundread metres say, then the nRF24 devices are a reasonable choice, well known and with lots of examples.
If you need longer distances, say a couple of km line of sight at 2.4Ghz then LoRa devices are probably the only (legal) option and capable of sending a 8 byte RC packet in 900uS with LoRa and in 100uS in FLRC mode.