I don’t agree with your handyman on his “every seven years” plan. Water heaters can and do last far longer even unmaintained. On the other hand, the stuff you found in the element ports sounds very bad. I think that tank is a goner.
But now that you know about anode rods, there’s no reason your next tank shouldn’t last forever. I’d suggest that once it’s installed, but before you fill it, you try removing the anode on the new one and then replacing it using Teflon tape. There’s a good chance you can get it out because the pipe dope they use will still be soft. The Teflon will ensure you can check it in the future.