I have no experience with that tumbler, but it should get the job done.
You can certainly use that older brass, it should polish right up with some walnut or corn cob media and maybe some polishing compound. I tumble before depriming and it works well for me, others tumble before and after, and yet others tumble after. It is up to you, they will all work.
Regardless of what you do, there is a lot of lead dust in the area of the tumbler, especially when you dump it and separate the media from the brass. I recommend doing this outside, and with a respirator, or outside at the very least. This is the largest concentration of lead dust in the reloading process, and should handled accordingly. Some people may say i am going a bit overboard, but it is cheap and doesn't take a lot of time to just throw a mask on when you dump the media.