My girlfriend owns a canon EOS Elan II 35mm SLR and canon 28-80mm lens. I've been messing around with it more and more and decided to get a digital SLR so we can have two cameras. I ended up going with a used canon D30 bought on ebay.

Now I'm looking around at lenses. My first question, are EOS lenses and EF lenses the same thing? The specs I read on the D30 say it is compatible with all EF mount lenses. I read one website suggestion they were the same thing, and there are a lot more lenses listed online as EOS rather than EF. Just trying to make sure that I'm looking at the right types of lenses.

Also, does anyone have any recommendations for or against 3rd party lens manufacturers? I've been looking at getting either a second 28-80mm, a faster 28-70mm, or a 50mm f/1.8 prime lens. Besides Canon, there's some models by Sigma and Tamron. Are these (occasionally) cheaper brands passable for someone just getting started, or are they not worth it?

Thanks for any advice you can pass along!