I didn't see studio monitors on your list, but trust me. Get a pair. You don't have to do it this very minute, but once you're in your new crib, you're going to need them to figure out your room acoustics, and how your shit sounds exactly. Plus you probably won't have any banging on the wall from nosy neighbors.
A mixer is always a must for a growing studio. They don't have to cost an arm and a leg, if you're willing to go with Behringers, but some mixers can have more noise than others, so research, research, research, and try before you buy if you have Guitar Centers in your area. Get as many channels as you think you'd need, and room to grow if you find any other gear you'd want in your setup. If you buy a mixer you'll grow out of, you can always upgrade when you need to, but if you buy one bigger than what you need, you won't grow out of it for a long time.
If you add another keyboard, you can always go analogue, virtual analogue, or just get a nice bread and butter digital keyboard or rack module that will give you plenty of sounds. If you need a good bass sound, you can't go wrong with analogue/va, but they're not good at symphony sounds, most acoustic instruments (piano, guitar, oboe, etc). So a good Triton or Motif would have you covered on most of your sounds. But if you're on a budget, just check out what's out there in your local pawn shops or ebay.
Almost forgot, since you're already adding your laptop to your setup, you don't even really need to buy a ton of gear if you didn't want to. Just get Reason, Ableton Live, FL, or whatever you see yourself using, and just get a bunch of virtual synths and effects right there off of the net. You'll have to decide what you're looking for, but chances are, it's out there, or will be soon.
Good luck.
console mixer