OK, chiming in regarding the hood. I've use the Simplicity 5840 pattern with success. this is a "Jedi" pattern that can be adjusted as you see fit. It's the hood used in my Avatar. I also used it last halloween when I made a Cosplay for Disturbed's "The Guy".
The pattern has a 'witches peak' at the back (WHYYYYYY?) - I modified this by just rounding the pattern at that spot and not pointing it. This also lays out well if you don't want a seam down the middle/top, which... who does? LOL. If you want a slightly wider hood, you can modify the fabric pattern as well.
ALWAYS cut out an intermediate/mock-up pattern piece first - I use old sheets from the Salvation Army or Goodwill (instead of muslin) - it's cheaper!) this allows you to quickly see any flaws and make adjustments prior to cutting out on your expensive final fabric.
Plan on lining the inside of the hood with a matching, inexpensive fabric. In between these layers, put a layer of medium weight Interfacing fabric, it's usually white. There is 'iron on' types, but i end up sewing it in just to be sure. don't get too light or too heavy of an interfacing. JoAnns Fabric has a large selection to choose from!
As to the mask - what the others have suggested would probably work the best. Just remember, your face will get moist with all that contained breathing, so something that allows you to do that without too much containment will be best.
EDIT: Reread your reference to the Balaclava... if you don't just want to get a black Balaclava and use that (aka Ninja), just get an inexpensive one and use it to create a pattern for the fabric you DO want. OR cut out fabric to go ON the existing Balaclava.