The GX100 stands well apart from 99% of point-and-shoots, largely due to its lens, RAW file option, metal construction and unique accessory EVF. They're hard to find (only two US dealers) so buying one is an act of faith.
It's not weather or bounceproof, so you'd have to take reasonable precautions. Because it's very small, you can keep it handy in a weatherproof pouch between shoots, so it's not as bad as stashing, say, an slr in a backpack between uses in bad weather. There are some reports of getting dust inside the lens and even onto the sensor, which has to be cleaned by a service tech. I don't know how widespread this is.
If you search Flickr for GX 100 you'll get over 40k hits, so there are plenty of samples to review. Talented photogs are getting great results from it.
And there's a thorough review here:
Like any small-chip camera, there will be noise at higher ISOs, especially shooting jpgs. The good news is that shooting RAW allows you to avoid any problems with in-camera noise processing or color balance. BTW, Ricoh RAW files are in DNG, which is Adobe's standard format, meaning they should be editable with any OS.
I've handled one, and am impressed at the small size, the build quality and the terrific WA lens. There's literally nothing like it. Its GRD II stablemate is an even better camera, but you have to dispense with the zoom, which many won't like. The DP1 is a whole other kettle of fish, and with good light it really does deliver slr-quality shots. There are flies in the ointment, however (true of literally any camera).
Can't help you on a primer, but there are a gazillion photography sites, and reading camera reviews is actually a pretty good way to sort through the controls, file formats and the like. I had to bite the bullet two years ago and simply buy a digicam and force myself to learn. Luckily, most allow success literally from the box, and digging into the controls you'll get better quickly. The laws of optics, luckily, still apply :-)