Since you are just starting off I think you need to set your goals within reason. To obtain a plant the size you are seeking indoors is not impossible it's not just very likely. A four foot Indica dominate plant is a nice one indoors, and would take at least 3 if not 4 months of veg time from seed. I have grown some pretty good sized indicas from clones that were over 32 inches tall when put into flower but I have never had one over maybe 50 inches at the finish.
A 4 inch inline fan will take care of the heat from a 400 watt light but a 6 inch is better.
With a 4 inch fan you will need 4 inches of passive intake. A 6 inch at least 6 inches.
Just starting out 3 each 3 gallon square pots will be plenty big for flower.
Yield is one of the unknowns but if you can raise 400 grams or 1 pound of dried and cured bud under a 400 watt light you will have a very sucessful grow.