In terms of your air exchange, we would need the cfm rating of fans. If you’re running the ac infinity fan as intake and vivosun fan as exhaust you’re probably ahead of air exchange requirements anyway. That setup may leave a little to be desired for temp control, but too many variables involved there to just say your fans will do it. How much heat you create in tent, temp of intake air, ductwork, and others will play into that. We have a guy that can help. He’ll just need that information.
Soil and nutrients, that’s a toss up. Promix is probably a fan favorite here. Its relatively inert so you would need to feed for duration of grow. The extreme opposite would be a heavily amended super soil in which you would likely feed very little or at all. A soil like fox farms ocean forest would get through a standard veg cycle without feeding much or at all. You kinda have to decide what you’d want to do there, and then nutrients and how you use them would fall into place. Most of the nutrient companies all use the same handful of compounds to make them. So the difference from one line to the next will just consist of different or more/less bottles with different ratios of the same stuff. I guess what I’m saying is that spending $30 or $130 wont get you any magic potions lol. Some just offer ease of use while others may offer the ultimate control and a few more specialized components.
Odor is tough. Most filters do a nice job, but are susceptible to things like high humidity and dust. If you have a filter that’s sized properly and no air leaks I would think you’ll be ok as long as environment stays reasonable. You probably wont need filter first couple of weeks. But late veg and definitely flowering they will stink.
Plant count another difficult situation. 4 plants on 4-5 week veg time wont be a problem. But you can do 2 plants first and get a feel for how they fit. Mixing indica and sativa can also be a problem. But plenty manageable if you’re not planning on growing huge plants.
Tap water could be fine. Do you have a well or municipal water?