Questions from a fellow grower:
I am preparing to start a growing business for medical marijuana. I will be growing in two 30’ x 90’ Rimol greenhouses. What are the average yields of God Bud and White Widow plants respectively?, ( They’ll be raised separately). How much space do I need per plant?, How many crops should I be able to harvest annually?, and what would the estimated value be?
There are a lot of intangibles that go into what something will yield; however, a basic google search, along with the data listed right is the ILGM seed section lists God Bud at ~900 gm per meter squared, and WW at 400 - 500 gm per meter squared.
Obviously, without knowing much more than just these being greenhouses, this is a rough estimate based upon the gods at the Google. 
This cannot be answered truthfully. Depending on how you grow, and what type of methods you employ will dictate the result.
Another factor is where in the hemisphere you are. Yield and grow periods (seasons) are going to more fruitful and longer in Zone 8 than Zone 5.
The spacing of your plants is proportional to the size plants and pots used.
Maybe you should download and read our Free Grow bible, in order to gain some foundation of knowledge before you undertake such a big grow project.
You can also hire an experienced greenhouse mentor. I am available for a fee + travel expenses. 