it is untreated and has absolutely no chemicals on it. All Lumber materials have the prop 65 warning because of sawdust.
If the wood you purchased has been treated, I believe it would last longer outdoors; however, it should still do very well. Plus, you can always stain or treat it yourself if you so choose. Hope it turns out fantastic.
Yes. As for what finish I would go with a nice stain and polyurethane.
I’ve done walls and wainscoting that way, but never floors. Don’t know why it wouldn’t work, but pine floors will wear faster than hardwood. I’ve had good success with poly on countertops. Good luck!
Yes. I purchased one at my local Home Depot, they are usually in stock.
This wood is too porous for that application and will mildew and mold
Use pressure treated lumber for that application.
You should use pressure treated lumber for outside applications.