Sub cabling help needed please

Since you are wiring for the sub, you will run the same type of cable from the wall to the sub's amp as you are running from the wall to the receiver. These all use RCA plugs. For speaker wire, run speaker wire. You can get wall plates to banana jacks for the speaker wire.

Sounds like you got a Monoprice wall plate. The 'easiest' would be to buy one of these and replace the subwoofer connector on the reverse of the plate. It's only $0.65, but I understand the whole ordering, paying for shipping and waiting thing can be a deal-breaker. If you're going to be buying other stuff, though, it's a very good solution.

Your subwoofer has its own amplifier, and there's no need to attach any kind of speaker wire to it at all. Your Pioneer receiver has at least one, maybe two subwoofer outputs, which is/are RCA. You run RCA from the Pioneer to the back of the wallplate (once it's modified by the connector I linked to.
Then you run another RCA cable from the wall plate to the subwoofer. The sub will indicate which of the two (red and white) should be used for line-level/low-level signals, or it doesn't matter. To be sure, you can always buy an RCA splitter like this or this, and connect to both inputs the single RCA coming form the wall. I'd recommend the latter (cable) splitter in case the spacing of the RCA sockets is different on the sub.

Actually, I just checked the manual for your sub, and you can use either red or white input or both using a splitter like I showed you above. It's all in the manual that I've linked to (around page 6-7), and there's even a diagram.

You can get RCA subwoofer cables from monoprice at very reasonable prices. Again, you'll need two and an optional splitter.

You're welcome, DonB. I've spent about $3K with them in the past year wiring up my house. With their prices, you can imagine how much wiring that is! My home theatre is ready for, or has already: a big screen TV, A motorised drop down screen, a projector, 7 bass-shakers (e.g. buttkicker), 14 speakers in-wall, an in-wall 22" touch-screen, plus four stations that can each hold: a gigabit ethernet connection, a subwoofer, stereo RCA component (e.g. a DJ booth) and an optical digital audio connection.

The touchscreen is connected by in-wall HDMI and VGA. The projector is connected by HDMI and two ethernet cables, with ethernet-to-HDMI adaptors at each end, and a 12V trigger cable too.

All of this was bought from Monoprice, and this is just one of the three rooms that are wired like crazy!

I kept saying to myself,"Better to do it now, than when the sheetrock is up!"

It would be nice to have a picture of the back of the 7.1 wall plate. I suspect that the single RCA on the front side is connected to an F type on the back. F type connectors are what you find on coax antenna cables where the center conductor is also the pin and the housing ties to the shield and screws on to the socket. For this, you can get pre-made coax cables that are long enough to make the run. Get another wall plate for where the sub will go and that has the same insert as the 7.1 plate has. Then you just need a standard sub cable to connect from the wall plate to the sub's low level input.