Replacing anode on water heater

Does draining the tank annually remove the sediment in the bootom and prolong the life of the heater?? How easy is it to replace the anode . . . or is it possible? Just askin'

Yes draining tank improves longevity efficiency. Turn off heat,turn off water supply to tank, allow to cool, attach hose to drain, open drain valve, open a hot water faucet somewhere. Preferably one close to tank low like in bath. Or loosen outlet on tank. When drained, turn on water supply for five or ten minutes to stir up sediment. Turn off water supply allow tank to drain. Some folks back flush thru drain hole a few minutes to stir up sediment, then drain again. A few seconds back flush may clear sediment from drain valve, you still may need to put hose cap on valve as it may not seal back, especially if you have not been draining regularly.

If electric, some actually remove lower heating element and use shop vac to remove sediment.

Close drain, retighten outlet, and open hot water outlets, remove stem from that low faucet. Open inlet valve to tank, watch low faucet to see that no sediment clogs valve. Turn off water to tank. Install stem, leave faucets open, start filling tank. Turn off faucets when they stop sputtering air, working from low to high. Turn on heat. Expect some sputtering when turning on hot water faucets, don't get splashed. Heating water releases some air.

Replacing anode keeps tank from rusting. Some hex head anodes you can remove with crescent, open end or box wrench, others require socket. Plumbing supply house, maybe big box have inexpensive sockets, wrenches for other type anodes, or go ahead by big socket that fits your ratchet. When taking out anode, especially if old, be careful not to break it and let it fall into tank. Won't really hurt anything it will continue doing job untill gone, but chunk could clog pipe or faucet. If you have low overhead there are jointed anodes made of short sections. Sort of like link sausage.

I use the drain cock as a source of hot water in the basement.

When it finally clogged with soft and hard very white chunks of material I turned off the gas and put enough cold water into the tank so I wouldn't get burned and then unscrewed the valve and had a makeshift pipe to transfer the water and particles from the pipe stub to a basement drain.
You could also make a small wire loop at right angles to the end of a coat hanger wire and scrape out the bottom of the tank.

If bad things happen while removing the anode rod some hardware stores sell a hard rubber plug that expands as you tighten the bolt that goes through it.

Edit: from anode to pipe reads 0.1 vdc and it passes 0.1 uA of current. I don't have a clue if I even still have an anode rod.

Depending on water conditions and type of anode, the average life expectancy is 4 or 5 years, less in soft water, even less if a water softener is used. Average life of tank is ten years. Ten year life is due to not replacing anode, with regular replacement tank can last 20 30 who knows how much longer. Water heater manufacturers recommend replacing the anode every two to four years depending on the hardness of the water and the quality of the heater lining.
Check anode by unscrewing and lifting part way out. New rods are 5/8" to 3/4" usually at smaller end of range. If 1/4" rplace it, certainly replace if inner wire core is exposed. If a relativly long piece should break off and fall in the force of incoming water could possibly cause it to bounce around chipping glass lining.

Once the anode is gone rust of iron tank starts immediatly even if lining is intact, there are gaps at connections. Three metals used in anodes, if tank has more than one anode replace all unless you are sure which metal is used. Mixing metals shortens tank life.
Aluminum is used in hard water locales, in soft water they last a year or two, water softeners use sodium, anode may not last a year;

magnesium is for softer water, magnesium is usually supplied with heater, in hard water it may not last a year or two,

zinc: actually aluminum with zinc added, used to combat sulfer smell

You really want to replace the anode B4 corrosion of tank starts, but later is better than never. "Spare the rod, corrode the heater." The thicker the rod the better.