Is this cart work well? What car seat does it fit?

Yes,the roller works well，, it's suited for those heavy / light travel car seats. it Holds 100 Pounds , it's great for pulling car seats or luggage at airports,

Does the included straps work well?

yes, it contains 4 ropes, 2 elastic cords and 2 straps, the straps are key to securing car seats,You need to follow the instructions to use the luggage straps correctly.

What is the quality of the cart? and any other uses?

Good quality, it can be folded, portable, with 4 wheels, in addition to the car seat, but also use at home, office and car , you can place it in the car trunk.