copper wires

[Enigmatical]

alright guys, so i thought it would be easier if i just showed some pics. the first 3 pics are of the speaker which looks the worst in terms of the copper not going through completely. the other 4 look better than this. as you can see, the red and black are pretty far from each other and in no danger of touching, again 12 awg wires. the last pic is the one of the AVR, and there too, the copper looks fine, however done w/o banana plugs because the ones i ordered from monoprice, not the screw side ones, but the screw in from the bottom ones, did not provide a tight base. so i guess my ?s are:
-i ordered 16 awg, should i just change all the wires because in the end any copper bunching up like that is not a good thing (based on the pics, or does it look ok)?
-i know i could re-order more banana plugs, but is it ok to use the ones i have and use electrical tape to keep wires in place in back of AVR?
-finally, given the distances, 12-15 ft max from AVR, there should be no discernible difference btw 12 and 16 awg sound, correct?

Thanks again guys, really appreciate the help!!!