I'd be somewhat reluctant to fertilize if your clarity is 24 inches. That's close enough to ideal that it might not be worth the risk and expense to fertilize. Your clarity could drop to 6 inches in a hearbeat. Our soils in Eastern Nebraska are naturally fertile enough that nobody EVER fertilizes. Careful, careful.
I personally like crappie in spite of the fact that they require more intensive management. Be ready to keep your bass numbers a little high and participate in "angler harvest" of the crappie. Also, you should resist the temptation to add crappie from nearby lakes because of the fact that you will be complicating your situation if you get both black and white crappie genetics. Get them from a very reliable source who can get you just the species you desire. You'll have to decide between blacks and whites--my personal preference is black crappie for clear ponds.
I might be the least knowledgable person on this forum when it comes to numbers on initial stocking, especially when it comes to more complex fish communities. Remember that you can always ADD species, but it is very difficult to subtract.
Keep it as simple as you possibly can initially.
