i have a yamaha 6.1 system with speakers that are very similar to what you have and i am torn between if i like them or not . i am certain that i do not care for the way they play music from compact disc weather it is stereo or 5.1 or 6.1 . watching movies on the other hand with this set up is ok for now ,if money were no object i would replace them with something better . i should mention that i have a yamaha 6.1 receiver with matching dvd changer .
as for speaker wire , i think 18 gauge should be adequate for small speakers rated at less than 100 watts it is what i am running , but upgrading speaker wire is always + .
the energy system has caught my eye once or twice it looks like a good deal , but if i were in that far i might take a look the mirage nano sat system , the way the tweeters are diffused makes me think imaging for 5.1 would be awesome and i would have think for the money this system would deliver a bit on playing music http://www.crutchfield.com/p_653NANO51B/Mirage-Nanosat-5-1-Compact-Home-Theater-Speaker-System.html?search=mirage+nano+sat