The size and weight of the anchor will also depend on the loads you typically carry, the currents you normally face, how easily your boat drifts and the bottom surface you fish over. You can almost never got an anchor that's too big (unless you're being ridiculous).
For length of rope, you typically want to go with a length that is 5x the depth you normally fish. Others will tell you that you can get away with 3x the depth. I fish the ocean a lot so 5x is what I use--ocean waves can be more temperamental than the freshwater waves I face in the West.
You will also get jerry rig/MacGuyver advice about rope and chain for anchors. If you want the cheap route, go to Home Depot and get any kind of rope, but truthfully you probably want some kind of braided/twisted nylon with or without polyester. DO NOT use polyproplene rope as it will give out on you (it's what's used for wake boarding and stuff). Boaters use a "rode", which is a fancy term for chain. Chain connected directly to the anchor will help you set the thing because of its weight. Then you connect the rope to the chain/rode and the other end connects to your boat. Use anchor shackles for the connection. Lastly, if you want to ensure your rope will last and not be frayed by its connection to the chain, use thimbles or rope that already has pre-assembled thimbles.
Remember, I'm suggesting what "boaters" would do, which is not necessarily a "bass fisherman" thing to do. As mentioned, others successfully and happily use a block of cement or even dumbbells for anchoring. I have to be a bit more serious because I fish the Pacific very often.