I have a Epiphone Les Paul right now and usually hook it up to an old keyboard amp I have lying around. The problem with this is I have virtually no effects and little tone control. In the short term I was wondering how hooking up an effects pedal (I was thinking Zoom G2.1u) up to my keyboard amp would work.

In the future I'd like to buy an amp for around $600 - thats versatile within the classic rock realm (Allman bros, Cream, Zeppelin, Pink Floyd, Hendrix, GnR...etc.)

Any input on either or both is really appreciated since I don't know that much about this stuff.

Thanks in advance.
For Amp's, a good fender tube amp like the Delux or DeVille (maybe a little out of the price range) with a marshall sounding gain pedal - i.e. Tonebone Hot British, would get you close to some of the tone's you're looking for. E.g. Allman Bros, Cream, Zepp, Hendrix and GnR, but Floyd is a completely different animal. That takes a lot more to nail down!

As for other advice, I'm not in a position to answer sorry. But the sooner you get a proper guitar amp, you'll be good to go! Just get away from the keyboard amp it's doing you no favours mate!