Need help with Ventilation! ASAP Ordered my soffits already

Hey all,
my husband and I are currently building a straw bale house with lime plaster.  We will be doing spray foam insulation for all of our ceilings. And that got me thinking about ventilation issues (this is not a subject I fully understand - I wish it were as easy as opening a window? haha)
Is there any system or idea that any of you would recommend for a more natural ventilation?  It will be passive solar and yes I do plan to have windows open, as well as exhuast fans in the bathroom and kitchen but I am thinking I would need more than just that.  I just have no idea what I should be looking into?
We live in North Dakota - so windows will not always be open during the cold months.
Does anyone have experience or input on spray foam insulation?? I am starting to question the "toxicity" of it all now thinking more about it. Are there any cleaner alternatives? This just occured to me right now and we ordered our soffit without any ventilation so I need to figure this out ASAP!
We have videos on youtube (Channel is called "building Roots" ) if youd like to check out the design at all. Maybe I can find a picture to give an idea of our build.
Also, we have cathedral ceilings, so If there is anything else we need to be taking into consideration please feel free to tell me all!
Any feedback would be greatly appreciated!
Thank You

I don’t know how to help but what you’re trying to do is impressive. I’ll be following to see what advice you get. Scott

Its possibe to get heat exchangers which capture the heat in exiting air.
They are excellent.
German passive houses

This site has lots of info about insulation and ventilation.

ok thank you both, i will look into that as well as other posts relating to my topics!