I salvaged this old 1-10 signal meter from a satellite system. Is there anything I need to know about it before I begin experimenting with my arduino? Where can I find a datasheet for this?
You don't. Assuming its a DC D'Arsonval meter movement, measure the meter characteristics yourself: full-scale current and meter resistance (determines voltage required at full-scale current). Use that information to help you connect it to your Arduino.
Signal strength meters used in communications receivers are typically calibrated from S0 to S9 in increasing strength of signal. Signals stronger than S9 are displayed as "decibels above S9". See image below: