that is a cute little bench vice, i would be wary of trying to do work that is *too* heavy on that though.
having said that, my idea of too heavy varies from others, 50mm (2") "wire" is light work for me ;)
i generally like to run parts through an electrolytic cleaning setup, if i deem them too rusty, and then oil them.
the spring needs to be replaced if- a) it is not there; or b) it is not opening the jaws up (which could be the spring, or a number of other reasons.)
you can clean and add grease whenever you feel like it, but if it hasn't been, or isn't being, abused, they don't need more than a basic look over every year or so.
enjoy, and keep collecting!