How to Remove Water Heater Elements

Yes, but if you run the water for a few minutes, it should release all of the air in the lines.

Yes. It is tricky, but possible. First, make sure you have turned the electricity off and that the water in the cylinder is cold. Stop the water from the main water stop cock, open a hot tap, and leave it open to drain any water left on the pipework and in the expansion vessel. Then, disconnect the hot outlet pipe from the cylinder. Through that hole, you can feed an inspection camera connected to your phone so that you can view it and asses its condition visually. After you are done, reconnect the hot outlet pipe, turn off the hot tap, open the main water stopcock, and then open the hot tap again to get out any trapped air. Now, go back to the cylinder and check for any leaks.

The elements come with a nut and a tool to remove them, so you don't need to know exactly. Take your info on the heater with you and you'll get the "gadget" that comes with the element to remove the element and replace!