Gonna start a grow using NFT
I'm jealous. NFT is one of the best yielders. If the power goes out, your plants die though. NFT is tricky to do properly. Be careful and good luck.

What sort of yield would each plant produce?
This answer is still the same and will never change: Six.

Do you recommend any ventilation products to help with heat distribution?
Only if you would like your plants to live.

What are the best seeds to start off using NFT?
The same seeds you would use for DWC, dirt, floating slabs, and all other kinds of grows: the kind that sprout.

Where do you recommend i buy genuine female seeds?
Kind Seeds. Descreet, fast, credit cards, friendly, good selection, gauranteed delivery. Only ordered once from anywhere, but spent a lot of time researching a good place. Very satisfied.