We have to wait until next week when the plumber can get out here to give us an estimate, but I need to get some sleep until then. Any advice on what we are to expect (price range, procedure, how long it might take) would be great! We had someone run a snake through cleanout in towards house. He said there is probably a very large root that broke a pipe. He couldn't get the snake to go very far back. Said we're in for quite an ordeal, but didn't elaborate on what that means. We thought they would have to bust up the concrete slab (which means tearing up our bathroom), but snake-guy and plumber-on-the-way both said probably only need to dig under the slab. Any advice would be great.

Yeah. Me too last week.

Some really bad news for me. Mine cost $7500 all in all. Snake + Camera to dianose + to bust up my driveway and repave.

If it's inside the house walls you may claim home insurance but they probably give you very little or else nothing at all. They claimed that the pipe has to be frozen.

Most home insurance companies will pay for the damages caused by the broken pipe. They will not pay for the pipe to be fixed. So they will cover the cost of restoring the floors or walls that had to be opened up to fix.
It is very rare that a root got under the slab and broke the pipe there. It is more common on the outside of the house. I do not understand how he got the snake to go from the cleanout towards the house. The cleanout is designed to flow towards the outside which causes the snake to move in that direction when it travels.
You need to run the snake from a cleanout within the home that is on the other side of the problem area, Or from a roof vent that serves the bathroom. I strongly suggest that you get someone with a camera to view the inside of the pipe before you tear out your bath or any other areas.

What is the issue your having?
When he cleaned the pipe did he pull out roots?
Is there a large tree near the pipe as it runs towards the outside city sewer system?