Okay, So I've been getting into alot of heavier death/heavy metal that involves a good amount of power cords and faster strumming on the lower strings. I'm using Extra Lights, and it just doesnt feel right. Whenever I get to playing fast on the lower strings, I can't seem to keep going without missing the string alot. Is this because I am a noob, or are the strings at fault here?

Oh yea, im using an Ibanez Gio
first of all, bull****. you wont miss strings because they're the wrong gauge. you miss them because you're not playing it right. if you're a noob it's because you havent been playing long enough and it just takes time to play fast and accurate. there is no right gauge for a specific tuning, but if you use light gauge strings with a drop tuning, like C or lower you will notice a difference. if you're using light gauge strings and playing in D, you won't really be able to tell. so basically just practice a bit more, if you're playing something fast, slow it down first and work your way up to full speed.
Jackson RR Professional, early 90's japanese model, with EMG's

Digitech GNX3000

Crate GX 212
Heavier or thicker gauged strings reduces slack? I'm about to buy a new electric but on my acoustic , I tried dropping the low E to low D and it's really flying all over the place when I play it.