I've never had any RTL-SDR dongle "auto install" the driver. Methinks HAMMYGUY used the CD at some time. Not really "plug and play", but almost as easy.
Yes, the upconverter does add noise, but the mod won't have the same performance as a complete board offering HF. And you'll not get 14-28mhz w/o a band pass filter. Might also introduce an ESD problem, so keep spares handy.
As I mentioned, I'm just an appliance operator, and would rather not take a soldering iron to my gear.
If you're one who is, some direct sampling mod info here: http://www.rtl-sdr.com/rtl-sdr-direct-sampling-mode/
But still, what a great "toy"! Sure glad there are gurus out there feeding hungry minds with new things to try!