Hotkeys should rather be for the spells, you want quick use of your spells be it heal, buff, damage, repair buildings, as that can be very split second. I just got started with hotkeys, someone did indeed advise me to use 1-4 changed with f1-f4, you don't need all 20 cards binded to hotkeys, rather just the spells and T1 units. I use my mouse buttons for spells though, w for first ability, s for stop, v to kill my own units, space for latest alert. Tho if you need to use more keyboard keys I think a moba based setup with qwerdf could help too
It could Depends alot on which decks you play too