Loud noise filling water

This important part is right at the end, you have a well!! It sounds like you may have run it dry? Check the well and the pump first. The rest is stop valves and pipes to the tank and beyond and not likely to be causing issues. Your sediment issues and problems with the anode is also due to using well water which is nearly always loaded with minerals..

Those things have limited life and once they start to leak replacement is in order.

One possibility: Push in the reset button located on upper thermostat.
Copy following link for troubleshoot walk-thru, and DIY checks:
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html#new

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Copy following link for troubleshooting leaking water heater.
http://waterheatertimer.org/Leaking-water-heater.html

You posted question under propane gas heater.
Propane is heavier and air, and this type gas water heater should not be installed in basement (below grade) since gas leak can fill basement with explosive gas.
Water leak does not cause gas leak, so water leak is separate problem.
Recommended for propane safety: install gas detector close to floor near gas water heater
Regular Natural Gas heater, install gas detector higher on wall since NG is lighter than air and will rise.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Luke warm water is the result of top element bad and the bottom is the only one heater. The best solution I can reccomend is to change both out due to the fact the bottom element may go bad and since you have to change one you might as well change both.

Turn power and water off, drain heater down and once water is drained out change them out. Once new ones installed turn water on to fill heater and open faucets and get air out on the hot side of each faucet once water is flowing out of each faucet you are now ready to turn power back on.

1) The pressure release valve is operating correctly and the sound it made is typical.
So pressure release is okay.
Always protect yourself from very hot water that can spray out of pressure release.

2) Rumbling sound is typical sign of sediment build-up inside tank, and usually indicates that tank needs to be cleaned out.
Seems odd that a brand-new tank could have sediment after only 8-9 months.
Did somebody recycle a 'new-looking' heater and sell it as 'new' heater?
Look at label on side of tank, and find brand and serial number to find actual age of water heater:
http://waterheatertimer.org/pdf/WaterHeaterSerialNumberDecoder.pdf

3) Because sound might not be sediment.
You can add a comment and it will send e-mail, and I will continue to answer.
No reason to be terrified of water heater. They are very safe, and homeowner can fix electric water heater same day for a few dollars.

4) Please listen to exactly where sound is coming from.

5) If sound seems to come from the pipes, and pipes are vibrating, then the plumbing is suspect, for example a check-valve, or pressure valve, and we can talk about that when you add a comment.

6) If sound is from inside the tank, then I suggest you turn off power, let water cool, drain water heater, open bottom of water heater, remove element, and check for sediment.
http://waterheatertimer.org/Clean-sediment-out-of-water-heater.html
http://waterheatertimer.org/How-to-clean-sediment-out-of-electric-water-heater.html

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TURN OFF ELECTRICITY before touching gas or electric water heater this is or was flooded.

Replace flooded gas or electric water heater.
Warranty is void, all manufacturers say replace water heater, and even if parts are replaced, there is no guarantee that unit will work again.
Resources:
http://waterheatertimer.org/Flooded-water-heater.html
http://waterheatertimer.org/How-to-install-gas-water-heater.html

Take a moment and rate answer:
And take advantage of fixya expert assistance live.
For a price, expert works with you while you work on water heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

The down tube inside the tank is clogging up with deposits

find out if it does the same noise with the venting disconnected