Generally the rule of slow cooking is to add liquid if the ingredients don't provide it itself. Chicken contains quite a lot of water so you don't normally add water to one when slow cooking it.
Trim fat - remove skin too. For bones in smaller joints of chicken you can remove part way through the cooking if you want, or leave until the end when the meat will just fall off the bone. Be prepared to have trouble getting chicken out - it really will come to bits if it's cooked right!