About the website's URL

Hi, there.

I'm currently on the free trial plan and I was wondering if I can keep the same URL for my website after I purchase the SCALE plan. Does anyone know if we can keep it the same or not? Also, can we still use the same website design we created in the free version?

Second, does anyone know how to make the "related products to this item" pop-up on the website?

Lastly, can we switch to the ENTERPRISE plan whenever we want? 

Thank you.