Thanks for the responses, guys.
Yes, the heater is mounted on 3 bricks.
About the anode rod. I tried to get one out of my previous water heater, and gave up. I also destroyed one of my wrenches on it. I think I'll leave this one alone. When I tried to buy one years ago at Home Depot, they didn't even know what it was. But they said they could order one, and that no one ever buys them.
I have already put some teflon tape on the threads of the plastic spout and screwed it back in, when I installed it 5 years ago. Still leaked.
When it's warmer I will see what happens if I tighten it up another half turn, or maybe more. Right now I'm afraid it will just strip and start leaking more, lol.
If the extra tightening doesn't fix it, I'll drain it and put a new drain spout in.
Will try to install new spout with water flowing out first, so I don't have to waste 50 gallons, and reheat it all.
I did drain about a gallon out today, and it was all very clear. Zero rust color or sediment.
Good to hear that if indeed it is only the external metal that is rusting, I probably don't have to worry.