Mary:
Actually the AR 2AX were pretty near the top of the AR line back in the day. If you are interested in
AR History , the highlighted web-site will fill give you a good background. I remember an AR product catalog from the early 70's and there were some performing halls which used series of AR 4's and AR 6's exclusively, which were below the AR2AX.
I would still advise to first hook all your equipment up and live with your system for awhile, before you take the plunge and purchase an additional amp (it will probably be a solid state amp, like a used NAD 370), for your front speakers. If you do decide to purchase an additional amp, hooking it up is straightforward enough ... you would hook up the front speakers to the power amp and connect the PRE OUT from your Pioneer Elite HT receiver to the INPUT on the amp.
As for speaker cables and interconnects, go with moderately priced cables from places like
AV Cables or
Signal Cables . Make sure that your terminate the speaker cables with the plugs that your equipment supports (it can be spade clips; banana plugs; or pins) ... ask your dealer. Bi-wiring can make a difference, ususally a subtle one, but it will also mean doubling your cable cost. Once again, I would go with single wiring and then see if you wish to bi-wire.
Regards, Rich