I might have this guy on my team, but i'd like to know if he's the fastest in the Unova region.
Yes, with a base speed of 145, it is the fastest Unova Pokemon. Second Place goes to Meloetta (Pirouette Form) with a base speed of 128.
Source: Bulbapedia/ List of Pokemon by base stats
Why, yes he is! Go here, and sort by speed. You'll see that Accelgor is the fastest.
Yes he is. After ou get the national dex you can get Aerodactyl who is faster but Accelgor is the fastest Unova pokemon.