Hey JackOfAllTrades.. for a set up like yours... I don't think you need any extra equipment. A system that can support CAT5e cables should be able to run your cables up to 600ft. I hear great things about CNB as well, but CNB runs its cameras via BNC, which means you'll have to run extra cables for power supply. If you plan on recording audio, you'll also have to run a third set of cables.
I have some experience with Samsung Security systems. They sell them at Sam's club or Costco. You can get a 16 channel system (SDE-5001). It's a Do-It-Yourself kit, comes with 8 cameras. 4 dome and 4 bullet. It runs all of its cameras through 1 cable (Cat5e). It comes with 60ft of cables, but I think you'll be able to make or buy your own Cat5e cables. I'll warn you, Samsung's tech guys will tell you that you might burn out your cameras...but they could be just saying that to cover themselves legally.
Anyway, my recommendation is Samsung's SDE-5001. It's about $1000 for the system and 8 cameras. if you need 12 total cameras, it'll probably run you about $1600. If you're going to run your own cables, Sam's or Costco won't do it...but i think you can find some online company who'll work with you... they'll probably give you credit for not taking the cables.
It has weatherproof cameras, it's at a decent price, and it's a Samsung. Remote viewing via smartphone and on your comp. I don't know, from what you mentioned, this seems like a good fit.
Check it out! Good luck