Strength is found on armor to lower your melee recharge and (I think) increases the damage versus non-players. Discipline lowers your grenade recharge time. Lastly, Intellect makes your super charge faster. Each bonus can be seen by hovering over their icons in the pause menu, where a percentage is displayed.

If you're using the hunter class, discipline and strength speed up the cool down rates for your grenades and throwing knife. You'll start getting intellect later that lowers the cool down for your special. Consumables are usually back-up amo types or things you can use to get more glimmer from killing specific enemy types for X amount of time. Materials can be used for a couple things. You can trade them for rep in the tower, but it's best to hold on to them for when you start upgrading legendary and exotic gear. Honestly, if you're playing the different game types and doing bounties, your rep will go up. I made the mistake of trading materials for rep before I knew about the legendary upgrades. Now I have to run all over and collect more to finish off my upgrades.