All the literature I’ve read says that chickens if cooked whole in a slow cooker should ALWAYS be cooked on High and ALWAYS on their own. I’ve got a mini (2 person) slow cooker and cook poussin’s in mine (approximately 1.5 hours). Always make sure you heat your slow cooker on High before you put the chicken in, any water/stock that you use should ideally be boiling; with the pot and liquid hot the chicken has less time exposed to coolness so less chance of any nasties getting in. You can use as much water/stock as you like, I just about fill mine as I like loads of gravy, if you don’t use much water/stock keep checking on it to make sure the pot doesn’t dry up. As to the skin, well it depends if it’s looks you want to go for; chicken in an oven has skin that comes out looking brown and crispy, chicken in a slow cooker has unfortunately rather anaemic slimy-ish skin (but easy to remove), it’s totally personal choice.