Backing up will have the traction advantage of more weight over the driven wheels.The e-Kona accelerates like a bat out of hell - be gentle with the pedal at all times is the only real thing to beware of, and yes the driving mode button on the centre console allows you to scroll through the three modes to eco mode - the mode you have chosen is briefly displayed on the screen to the right of the speedometer for conformation of which mode your press of this button has just changed into. Do not press this button whilst driving until you have driven the car for a while. Some people always drive in eco mode.
Regen is like quite like engine braking, just better, and with three levels it is something to play with over time.
As for hill climbing near your garage, accelerate slowly, don't back up or anything, EVs have instant tourque so backing up won't help. You will notice that the e-Kona climbs hills as effortlessly (and as silently) as it drives on the flat, if you accelerate too hard you will spin the wheels and potentially slide out of control. That solid low slung battery makes the whole car heavier which helps the grip level too.