From the Steam support page on extra copies, in most cases you won't receive extra copies of a game you already own when you buy a bundle that includes that game. There are certain exceptions, mostly relating to Valve's own titles, but Counter Strike is not listed amongst them, so you'll have to buy your friend the game/pack separately.
If you buy the pack as a gift, the giftable game in your Steam inventory will be the entire pack, so you can't split it up.
In some circumstances you will explicitly receive gift copies of games you already own. For example, with the recent Bioshock: Infinite preorder bonuses on Steam, they stated clearly that you would.
Humble Bundle packs and other such things may work slightly differently, because they give you Steam product activation keys (which are not yet bound to a Steam account) rather than Steam gift copies. Humble Bundle packages together games into a single Steam key when possible, but older bundles or games added to the bundle after purchasing may provide individual keys. Note that technically you are not supposed to share any extra keys you have.