Ok, in that case, do I need to remove the 3-chain ring gear, cabling, gear lever and front derailer?

Yes, you do. The motor comes with a chain-ring. You may opt, depending on your riding style, for a smaller or larger gear. As I said above, I changed to a 50 tooth insteaed of the stock 46 that came with it. The other stuff doesn't HAVE to be removed but real estate on an electric bike becomes a touch scarce. At least it did for me. Good luck. It'll work out fine. It's not rocket surgery.

I would imagine a higher tooth count gives you more leverage to climb a hill, but limits your speed on flat surfaces? Also, do you get use of the full range of gears on your front cassette with your 50 tooth chain ring? Mine is a 26" tire, 3x (24T, 34T, 42T on the crank triple chain rings), and a 7 speed freewheel on the back. Should I upgrade my freewheel to say an 8 speed cassette to get a larger sprocket on the back, for a better gear ratio to go up hills?