Welcome Noob. So with all yor experience I am sure you are on top of whether the motor will put out AC or DC, and what to do from there.
Horizontal will normally give more RPM, and better mechanical conversion efficiency. Thats why I have focused on HAWTs, and don;t know too much about VAWTs. Your smaller batteries could make a usable bank - nice for testing, and low risk in case something goes wrong.
I am not familiar with the products you mention. One thing... 3000W @ 12V?!?!? Have you calculated how many amps you will be drawing from your batteries? I think you will get the voltage dropping way down, and the inverter shutting down if you try and draw anything near 3000W.
Yes, the mechanics can be complex. Make some drawings, post some photos, and we can all have a look!