Killing in the Name - RATM

So I really want my first full song known (other than Seven Nation Army [ Thanks Dman]) to be this song. I've always liked this song a ton. I would prefer it be Sleep Now in the Fire, but that's just too damn fast for me. So I got these tabs: http://www.bassmasta.net/r/rage_against_the_machine/158386.html and don't know what the 'h' means. Can anyone clear that up? I can't really progress until I know what the h is for..

"h" is for hammer ons
"p" is for pull offs

so for the first part you'd play the third fret on the A string and then hammer your finger onto the fifth fret.

I seeeeee...Thanks you sir. Now I'ma figure out how to tune it down er whatever I'm supposed to do..

That main riff, the 3,5,3,4,5 [cant be bothered writing it out fully ] is something I had struggled with, getting the speed/accuracy and all when I first started playing. Its an easy song once you get the patterns and such down. Ima be doing a cover for youtube of me and aguitarist playing that song

It doesnt say on the tab, but it HAS to be in drop D. Which means instead of EADG, its DADG, you only change one string, its really obvious when you do that 000 666 000 666 part how important it is to tune it down, it sounds PERFECT when its dropped