Help for a new tech writer

[Jim Mezzanotte]

File this under "careful what you wish for." I've been trying to break into
technical writing, and now I've plunged right into the deep end. I'm working
for someone who is gearing up a manufacturing plant from scratch, and he
needs complete documentation for every operation that will take place there.
Seventy people will be operating the plant when it is up and running. My
background is in print publishing--minimal proficiency in Quark, and that's
it. He's leaving the software choice--and everything else--up to me.

Am I nuts to take this on? I will be starting slowly, a few days a week,
with research at the plant. All the info I will need is essentially in the
owner's head, so I will be doing extensive interviews with him. But I need
to get the right software and a template to work with so I can at least
start plugging things in to some kind of structure. I'm wondering about
Framemaker or Indesign.

I know I haven't given much info (I don't have much yet), but anyone have
advice for me?   

--New (mildly panicked) tech writer