Vienna ep on single computer helpful?

I’m working on a Mac, and don’t have other computers that could function as slave. Would it still be useful to use Vienna EP?

Yes it’s still useful, you don’t need a slave to use VEP. You still get the benefits if you need to use large templates (quick Cubase save times etc…, quick switching from project to project). I had a VEP set up like that until I moved away from orchestral stuff.

What about ram usage? At the moment I only have 8 gb because it’s a pain to install more on an iMac 21 inch computer. All the instruments are loaded into ram via VSL right? So Cubase will not use any ram for that.

Yes that’s correct.