I run Adamant.
As for the item, definitely Focus Sash, or Life Orb.
As a matter of fact, this was the first battle I used Life Orb Gallade in. It's necessary for getting some key OHKO's (in particular; Machamp and Swampert). Focus Sash has its uses, but in most cases, the opponent is going to Stealth Rock first, so you don't really need to be surviving any hits.
Check out this thread. There's a whole discussion about lead Gallade! :D