id go with thicker guage wire. if you are going to use wall plates, id solder the speaker wire to the plate. solder is not perhaps the ideal connection, but it will be the least problematic. then from the wall plates to the spakers, bananas would be nice. bare wire is fine, but it tends to become loose over time and will oxidize as well...

if you are going to put high dollar speaker wire into a cheap wall plate then that is silly.

i guess it all depends on what you want to have coursing through your walls, be it monster or "lamp cord", all of it will transmit the signal... however i would stick with in wall rated cable that is a low guage and is a good price... for your use, i would probably go with the cheapest lowest guage i could get from the likes of belden or canare... particularly if you are running the wire through a conduit, the amount of insulation/jacketing will not be very important, but if you are running the wire without conduit, the wire should be well insulated/protected from interference...

its really not the biggest deal, dont worry about it so much. the idea of home theather is to enjoy it, im sure most any wire that you would pick will allow you to do that.