if you have 5 ponds I would not mix several aggressive predators in the same 1/5 acre pond. SMB, WE and catfish in the same small body of water are going to create issues. If you want a walleye pond then let the walleye be the predator and pick your food chain under the walleye. If you have to have a catfish pond then realize the catfish will out-predator the other predators. SO that may be a stock and catch pond.

Walleye need running water over gravel substrate to spawn. Think a creek flowing into a lake. Some have had walleye reproduction, some have created water movement with a circulating pump. Others can speak to that better than I.

Catfish can find a way to spawn, with or without a cavity but usually if you want spawn/young you give them a cavity to spawn in.

Since you have 5 ponds to work with, I'd take your time and create your forage base first, then add YP or panfish of choice being careful that your panfish choice matches your apex predator. For example northern bluegill (or even hybrid bluegill) are going to overpopulate if you only have WE as your predator.