#1
So I have been wanting to learn some metal songs from some of my favorite bands. Some times I'm required to go a certain tuning for example, in this case D, G, C, F, A, D. I'm not sure if the standard strings that come with my guitar would handle the tension. I was wondering what strings are recommended to play this type of stuff?

(My Guitar)
http://www.guitarcenter.com/Squier/Affinity-HSS-Stratocaster-Electric-Guitar-Pack-w-15G-Amplifier.gc
#2
That is just standard tuning a whole step down, so if the strings you currently use feel a bit too slack, go up a gauge. It wont harm the guitar in any way, but the nut slots might need widening and the action might need resetting.
#4
If you haven't changed strings before, I'd suggest watching a load of videos, or taking it to a shop and asking to watch.

Other than that, maybe try an 11-49 set (Ernie ball Power Slinky or D'Addario EXL115).
#5
My normal tunings are Standard, Drop-D (Low E String dropped a whole step), D Standard (The tuning you were referring to, every string dropped a whole step), and Drop C (Drop D another whole step down)
And I use Ernie Ball's Skinny Top Heavy Bottom. They work really well for all those tunings