#2
not unless the current ones are too thin. (i think i've got the right bit of the guitar )

you will need to adjust the intonation though
I want to feel youre body breaking, and shaking, and
left in the cold,
I want to feel youre conscience making, a change to fix
this dying soul....
#3
Try them out first. If they dont fit, then you have two options, get a file and file out the nut or rub the strings into the nut and hope they can widen the current nut.
I've developed a complex where everytime I hear a Lamb of God song, I burst out laughing

My 7 String V build
My Main Guitars:
Kramer Striker FR-2027SM 7 String
BC Rich Afterburner Warlock
Washburn Xb100 Bass
My Effect(s)/Misc:
Digitech RP350
#4
You might have to. I remember that, on my old guitar, the 12s I used didn't fit very well in the slots. Best thing to do is see if they fit - that will give you the best indication of whether or not it needs doing. And as stated above, you'll need to adjust your intonation and, unless you're tuning down to something like C, you will almost definitely have to adjust your truss rod, too.
#5
remember to use some graphite (pencil) in the slots too.
within you lay everything
every key
every secret

untouched and in plain sight