VEVOR 3/8" Cordless Electric Ratchet Wrench Set, 12V 33 Ft-lbs Power Ratchet Tool Kit, 45-Min Fast Charge, 2-Pack 2.0Ah Battery, Built-in LED Light, Variable Speed Trigger, 10 Sockets

No, they aren't compatible with Milwaukee batteries.

All products on our official website come with a 12-month warranty. If you purchase a product that has a problem within one year, we will be responsible for you. Here is the link: https://www.vevor.com/pages/return-policy.

No, it has a brush.

I did not find any information about a carrying case in the product description or customer reviews.

Yes, it has variable speed control for different tasks. The product description states that it features a variable speed trigger for precise speed control.