Most good emergency service will recommend replacing a gate valve regardless of its condition. The time to discover if it will work is not during a flood in your bathroom. If you have it replaced with a ball valve then check your water heater and laundry valves, too. Have them replaced at the same time with premium ball valves. Ball valve laundry bibbs make it easy to shut off the water to the washer after each use which may help to prevent floods in the future.
If you find that the water line repair leak is in the supply line you will need to replace it or simply tighten it. Start by turning the water supply off and then flushing the toilet to get rid of the excess water. Now use the towels to dry the area so that it is easier for you to fix the leak. Use a wrench to loosen the hexagonal nuts on the supply line at the main end as well as the one which goes to the flush tank. Now use the replacement supply line which you have and tighten the bolt at the supply end first. Now adjust the length that you will need for the pipe to reach the flush tank. Once you adjust the length use a knife to cut the extra length and then tighten the hexagonal bolt at the other end.
A c clamp or hose clamp is use full for securing or holding the rubber used to seal leaks on piping. However, a clamp should be used carefully considering the type of pipe being repaired, clamping too tight will fracture the pie leaving you with a bigger problem than you started off with.
The next step in this process is to determine what type of method is available for fixing the problem. You cannot just caulk a crack or fill it in with cement and hope for the best. Unfortunately, there is more work than this because you have to fix the problem from both the inside out and the outside in. This takes a professional in most cases to determine the best method for repair.
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.
From your own point of view, it is important that the plumber be trustworthy and credible. Ensure the plumber comes with at least two strong references which you can verify. This will help you be more secure and suffer less anxiety.
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.