There are clog ways to combat this water damage disaster. Let's talk about the four steps you can take, to prevent this from happening to you and your family.
When you get to the house stand if front of the toilet and locate the water shut off valve. Should be down below the toilet on the wall. Just turn it off (righty-tighty) completely and flush the toilet. All the water should have left the tank, well at least most of it. If there is remaining water line repair get it out with paper towels or a rag. The important thing is that no more water came in. If it did then your valve is not shut all the way or not working and you need additional help.
You don't want to be paying your plumber to clear the area before they start work particularly if you are paying an hourly rate. Empty cupboards and make sure there is nothing that may cost the plumber time and you money gaining access to the job.
Getting advice from someone who has not made any money online is like asking a plumber to shoe a horse when they have never done so. Why in the world would you do this?
The water line repair most likely damaged your electrical outlets and lighting fixtures. Have a qualified electrician come in to evaluate and repair the electrical.
People who own rental properties are great ones to give you information. With all of the service people needed for maintenance on their units, they typically know who to call and what level of work they perform. Most property owners will be more than happy to give you the information you seek. In fact, they were probably in your shoes at one time.
The plumber you hire does not normally do heating but will do hot water heating or in floor heating in the house. Some places you can use the water heater for both domestic hot water and for in floor heating if the heating is a secondary heat. Check with your local plumbing codes on this to be clear.