Well I'll update this thread. I checked & cleared my carb & tank vents and everything should be ok with them now. I did take the quad out and do some mudding w/ a buddy and my quad ran fine with the Polaris Scrambler speedo kit disconnected.
Later, I checked all my wiring on the Polaris speedo kit, cleaned up its ground wire and then I did some checks with my multimeter and here are the results:

Stock electronics:
Volt tests:
idling: 14.3 volts
above idle: 14.6 volts max
above idle with headlights on: 15.03 volts max
Amp test (placed meter between ground cable & battery negative terminal):
key off: -0.000989 amp

Polaris speedo kit installed:
Volt tests:
idling: 14.3 volts
above idle: 14.6 volts max
above idle w/ headlights on: 15.01 volts max
Amp test
key off: -0.000984 amp
So, it appears that, electrically, everything should be ok, no battery draining or overcharging problems, right? Although, I'm not sure what to make of the 15.00 volt readings I get with the headlights on...is that normal? I forgot to mention that I can hear a clanking kind've sound while the engine is idling, it sounds like it's coming from the pull starter, pretty common, right?