Where oh where do I place my speakers

I just bought a Yamaha RX-Z1. This unit allows for front main (L/R), front and rear centers, Rear (L/R), and front effect speakers (F/R) I have a pair of NHT VT-2 for the front main speakers, I have four (4) NHT VS-2, and a pair of HDP-2 speakers. I was initially planning to use the HDP-2 as the rear speakers and the VS-2 speakers as the front and rear center and front effect speakers. I've heard that the HDP-2 make great side effect speakers.

1) Should I use the VS-2 speakers for the front and rear centers and the rear left and right speakers and use the HDP-2 speakers as side effect speakers?

2) Does it matter if I use side effect speakers instead of front effect speakers?

3) Where should I place the front or side effect speakers?

Dean