I just got my camera today! Its awesome looking LOL!!!
It came with 2 lens, the 55-200 zoom lens and the af-s dx nikkor 18-55mm lens
3 books you absolutely should have.
Digital Field Guide for Nikon D3100
Understanding Exposure
Understanding Shutter Speed.
all available on Amazon for $15 or less each. best 3 books you can have for learning how to use a DSLR camera.
those 2 lenses, they are cheap kit lenses. you can get decent pics with them, but save up your money and get some quality glass, the difference is amazing and noticeable. Sharper pictures, better color, better clarity. quality glass is expensive though, about $1000+ for each good lens, some run upwards of $2000.
since you're also a storm chaser, try to focus primarily on fast lenses (lower aperture #'s). f/2.8, f/1.8, f/1.4 and f/1.2 lenses. those will yield you the best results in low light situations.
I'd recommend these
14-24mm wide angle
http://imaging.nikon.com/lineup/lens/zoom/widezoom/af-s_zoom14-24mmf_28g/index.htm
24-70mm f/2.8 portrait
http://imaging.nikon.com/lineup/lens/zoom/normalzoom/af-s_zoom24-70mmf_28g/index.htm
70-200mm f/2.8 telephoto
http://imaging.nikon.com/lineup/lens/zoom/normalzoom/af-s_zoom24-70mmf_28g/index.htm
and a 1.4x extender. This magnifies each of your lenses by a factor 1.4x. Downside is you lose 1 full f/stop. so f/2.8 lenses become f/4 lenses.
the D3100 is a crop camera (not a full frame) so with it comes a crop factor of 1.5x, which means your
f/2.8 14-24mm = 21-33.6mm, add the 1.4x extender it becomes an f/4 29.4mm-47.04mm
f/2.8 24-70mm = 36mm-105mm, add the 1.4x extender it becomes an f/4 54mm-157.5mm
f/2.8 70-200mm = 105mm-300mm, add the the 1.4x extender it becomes an f/4 147mm-420mm
that will give you a nice long range for just about any shot you'll be taking. wide angle shots, portraits, and long distance shots. you can shop around at
http://www.b&hphotovideo.com
http://www.keh.com
and craigslist and ebay for used lenses that are cheaper than new but still quaility.
I'd avoid places like Wolf camera and best buy, you'll just get price jacked and overpay and I've not usually seen any really good lenses at Best Buy, mostly the 3.5-5.6 lenses which change aperture the farther you zoom in and you don't want those kind of lenses.
B&H is great to watch the few weeks before Thanksgiving, this year I saw the 70-200mm, go from $2499 to $1799 shipped on Black Friday.
When I was looking into which to use, I saw companies like Hasselblad and Leica used it, so I assumed (yeah I know) that other manufacturers did as well. Looks like Nikon uses .NEF for RAW. But for all intents and purposes RAW is RAW (most proprietary formats can be converted to DNG losslessly [is that a word? 
]), I think differences occur in the formatting of the card and 'wasted space'.. Of course the actual file size has a lot of variables but you generally figure on the high end about 1.5MB per MP for RAW, and then if you shoot RAW+, add up to 750kB per MP (depending on set quality) for the actual JPG copy.
