HELP with making a roast in the crock pot...?

This is my idea.. tonight before i go to bed im going to peel my potatoes... i heard you can even put the roast, and water, and carrots, potatos, and onions, and onion soup mix all into the crock the night before.. and put it in the fridge.. in the morning i want to put it on... should i cook it on low? and how much water should i add to the crock?? it is ok to cook the potatos all day along with the carrots.. should i cook it on low? im gone from 8-5 thank you for the help!