Keep it simple. Cant stress that enough, add a door between the flowering rooms and save all that money on curtains and the fact that odor ill pour out?
You are wasting a lot of space for air, 3x7 would be more than enough room for an A/C before your air goes outside. 9x7 for a veg room, and 2 14x7 flowering rooms. Get rid of the hallways??? waste of space. add doors, get rid of huge area in veg room, just make a small airlock, a small room to clean yourself and keep the odor in.
If you run a couple centrifugal blowers (i got one for 10" for $60 used only 250 retail anyway) Suck through some big carbon filters, one well place carbon filter per flowering room, hook up the blower to the filter and run your ducting. Seal off the flowering rooms as best as you can!
Your making this really complicated, and you only have 15k, the fact is I can blow 15k on 2 10x10 flowering rooms Easily.
15k will get you HOPEFULLY enough HID Lights, 4 massive carbon filters, at least 6 centrifugal blowers, all the extra little fans to get air moving in the room, Lighting alone for a grow that size could run over 6k, you will need probably around $1000 in just ducting! $200 on duct tape. 2-3k on fans. Money will go Fast if you try to make a super self growing super op, it would be nice but you need to get realistic on the cost of things.
Adding a hydro system will run MINIMUM 5k for that size, dont forget about all the little things, the extra water pumps for that size, all the reservoirs you will need, you could spend 2000 on pumps reservoirs alone easy.
You should be planning on what your going to absolutely NEED to do a Proper crop, then you can start optimizing, dont expect the first grow to go perfect, your going to want at least 3k for all the stuff that will come up during the grow!
Its easy to get excited about something like this but take your time and be realistic for what this could be costing you.
Growing is a simple equation stealth vs budget vs yield and it can be a difficult balance! I would seriously plan on how you can do a PROPER budget crop with Max yield and Max stealth for your budget, dont forget that things always change, by the time you finish your first crop your gonna have a million new ideas of what you wanna do with your space.
I really recomend looking at prices for how much equipment you will be looking at.
Im setting up my new house and its nothing near that size, my original thought was maybe 2000, but lights and fans and filters alone are costing me over 4k.