Mart, that tank is so cool, I also wonder what fish you have in it?
Spaghetti, I am not too sure about the freshwater crabs and crays. Here in the UK most of them are illegal because they can escape into the wild and cause trouble. The crays certainly will escape from their tank if they don't have a well-fitting lid. The freshwater 'blue lobster' must be kept on its own because if it dies it releases a chemical which kills fish and other lobsters.
Small tropical fish do have short lifespans, only 18 months for some guppies, 2-3 years for most small tropicals. It increases with the size of the fish - big tropicals and coldwater fish may live for 15-20 years or a lot more, but that then raises the question of how to house a huge pleco or 20kg carp.
Sorry to hear that the angel fish ate all the others. As they grow, they tend to eat small fish. Most fishkeepers have had a few disasters like that.
The Bettas should breed if you get some females, but unless you separate them from the Botias the eggs will get eaten. The male makes a bubble nest and attracts the females to it. Courtship is quite rough, and the females may get torn fins. The pair wrap around each other as they spawn, and then they separate and the female floats away as if dead, but then recovers and swims off. The male collects the eggs and spits them into the nest, then he guards the nest. The female may be bullied by him and should be removed after spawning. When the fry hatch it is better to remove the male, as he may eat them. They are very tiny and difficult to see, about 2mm long. As they grow, the males need to be separated from each other.