Congrats on your Riva purchase. My eGo croaked recently and I ordered the Riva SE from Sweet-vapes too, they had a good sale and disount code too. I am more than happy with it, and with Sweet-vapes customer service. Their juice is pretty good too, not the best, but better than most. I would take Swedishfish's suggestions on purchasing the extras, I already had most of that stuff, otherwise I would have had to put in a second order. You should really have an atty, drip tip, etc. I also like the eGo Mega Dual Coil Cartos, and would think about ordering a couple of those to try also. As far as shipping, I ordered mine on a Monday night and had it by Thursday morning, and I live on the West Coast too.
Your issue with vaping a ton could be for a several reasons, not enough nic content could be one reason, getting acclimated to vaping could be another. When I first got my PV, I was huffing on it constantly for a week or so to feel satisfied, but now not anywhere close, it's less often than I would actually go smoke an analog. I think it was just a matter of getting used to it. Stomach pains? No idea... have you eaten? Withdrawal should be little to none. I never had any withdrawal issues, and most that I know haven't either, which is one reason this is such a nice alternative to smoking. Of course I never tried one of those gas station things either so wait for your Riva, and see if that doesn't fix most of your problems.