The obvious race choices are those that can boost your INT: Eladrin, Tiefling, and Human. Tiefling is a good choice if you also want to use some Inspiring Warlord exploits. Otherwise Human is probably good. The Eladrin's extra dex is of minimal use.
For at Wills, take Commander's Strike & Wolf Pack Tactics (good for setting up flanking), if Human, you might also want Viper's Strike, especially if your Defender isn't a fighter, as it helps keep an opponent from shifting with impunity. For your Encounter Power, Leaf on the Wind is ideal for setting up a flanking, or Warlord's Favor leverages your INT (/if/ you hit). For your Daily, Lead the Attack is insane with a high INT Warlord (again, /if/ you hit - if Human, use it with an Action Surge, and/or get some bonuses from the rest of the party - flanking, Aid Another, etc - to make /sure/ it hits). Alternately, Pin the Foe is pretty good, and it's effect aplies whether you hit or not.
Hide Armor is definitely the way to go. A Polearm is a cool idea (lets you use your exploits from reach), and with your high INT, you might be able to do without the extra defenses of a shield.
Multiclassing to Wizard is an obvious option because it leverges your high INT. Scorching Burst is probably a good choice, for the AE - it's an at-will that's still nice even as an encounter ability, mainly vs minions. How deeply you want to go into multiclassing is a question, though. While being able to use your INT to hit once in a while will be nice at low level, splitting resources between a magic weapon and a magic implement gets inefficient, and, according the common on-line wisdom, Wizard of the Spiral Tower isn't an option (the feature that lets you use a sword as an implement is open only to wizards who "specialize" in an implement).
