Cats tolerate temperature different than most other fish. "How deep" isn't as important. Look for sharp depth changes (even if it's 5ft down to 8ft), logs, weed lines, if it's a dammed creek where the channel is, changes in bottom texture, etc....just like you would for bass. I've caught 7-8 pound channels in less than 18 inches of water in the summer during the day. Cats are predators so relate to all those things so they can ambush baitfish. They are either resting in a dark concealed place (in grass, under logs, etc) or they are moving around looking for opportunities to feed. Either put your bait in front of them where they are resting or in an area they will be hunting.
Location is more important than bait but I ALWAYS use some punch bait and some cut bait and see what they go after more. Usually mixed but sometimes catch 8 on punch and 1 on cut or the other way around, good to have a mix.