For both kinds the tuner error is ~30 -20 PPM, relatively stable once warmed up, and stable from day to day for a given dongle. The RTL2832 ADC differential input impedance is ~3,300 Ohm.The dynamic range for most dongles is around 45 d B.
My favorite way to explore the spectrum is using rtl_power to do very wideband multi-day surveys.
Originally meant for television reception and streaming the discovery and exploitation of the separate raw mode used in FM reception was perhaps first noticed by Eric Fry in March of 2010 and then expanded upon by Antti Palosaari in Feb 2012 who found that these devices can output unsigned 8bit I/Q samples at high rates. rtlsdr as we know it today was created by the osmocom people in the form of rtl-sdr and osmo SDR, keenerd is the author of many other rtl_* tools: rtl_fm, rtl_power (heatmap.py), rtl_adsb and code changes accepted into the mainline. The dongles with an E4000 tuner can range between 54-2147 MHz (in my experience) with a gap over 1100-1250 MHz in general.