Tried a mix with Cubase onboard stuff only incl. the channel strip. Depending on the basic materials it can take you far. But keep in mind that it’s bread’n’butter processing. Special tasks may require special tools.
Channel EQ: simply great for a channel EQ.
Comps: well, they do compression 
Of course not as tweakable or characterful as some others but still useful.
Envelope Shaper: great thing. Maybe behaves a little strange at extreme settings.
Saturation: not sure. Always better when used just a little (if at all) in my ears.
Limiter: not much use for limiters on individual channels here. I like the brickwall one.
Presets are more or less a waste of time. They represent what somebody has done to a certain source which will differ from your signal. Going from scratch is the better idea.
After a long time away from music, I’d recommend to see (hear) how you can get most out of the given tools. Just to get yourself a feeling of the limits. Take it as a basis for deciding what more you really need. There are a lot of really great freeware tools out there (i.e. the legendary Bootsy plugins: http://varietyofsound.wordpress.com/ or the free bundle from Meldaproductions: MFreeFXBundle | MeldaProduction), as well as inexpensive goodies (i.e. SKnote: http://www.sknote.it/). And of course a lot of higher priced products (Slate Digital, UAD, Waves). But even the free stuff is often better than what money could buy in hardware 20+ years ago.
Have some fun 