Depending on what digestive enzymes you have (or rather how far you want to stretch the bottle you bought) I don't think it's a bad idea to take them with every meal! Even if breakfast doesn't give you trouble, the enzymes are just helpful all around as our bodies are figuring out what the hell is going on. Haha.
The Cholestyramine definitely helped itching for me so it's worth asking your doctor about! Really, I tried stopping it for a couple days to see if maybe I didn't need it anymore and the itching came right back. I've seen stuff about its effects on absorption too but the info online pertaining to that is really vague so I'm not sure. I'll have to ask my nurse about that!
Good luck!