And, is it okay to provide customers a link from my description of my free model with limited non commercial license to a website where customers can purchase a commercial license for the same product?
I believe there is a few subscription based websites that allow you to use models and sell with a license.
Yeah you see it all the time on here, it’s normal - (having say a single model from a family that has a pricepoint elsewhere) some of the most successful designers here do it. The common ones are Printables and Thangs (many others) I know Cults3D is popular but they’ve got a terrible track record of compensating those who sell models to the point that you can’t type Cults3D into the 3Dprinting reddit because they’re banned, so personally I’d avoid them, but the others are well known and legit.