Tubing is measured at the inside diameter, so yes, you need 1/2" hose to fit on a 1/2" barb.
Is this at the bottom of a boil kettle? If so, then yes, get silicone (high temp) hose.
Keg #1: Brown Bomber Bourbon/Oak Vanilla Porter
Keg #2: The Bollocks ESB
Keg #3 Lawnmower APA
Bottled: Mjolnir Mead, Lazy Daze Hefe.