This is the basic set-up you need for a 2-channel model:

I would suggest a 2-channel radio with one servo (e.g. Hitec, Futaba); a 15A speed controller (e.g. ACTion P80, MTroniks Viper 15A) and a Mabuchi 555 motor (from Component Shop). You can use your existing battery, but if you find the model is too slow for you then you could always increase the battery to 12v.
If you want to fit extra functions such as a bow-thruster, lights or a horn then you will need a multi-channel radio. The Planet T5 is very popular.
Dave M