Please let me say first that I only have experience with car seats as a grandparent. When my daughter was a baby they did not have car seats that I am aware of.
I think Cosco makes one of if not the best car seats I've ever used. Now you should know that I've never "permanently" installed a car seat base. I have always used the seatbelts to secure the car seat in. So I can't say anything about the ease or difficulty in doing this.
I just know that all of my grandkids have all seemed to be happier when they were in Cosco car seats than any other kind.
Thank You