OK, here we go:

  I started a computer consulting business (PC Repair,
troubleshooting, network setups), and within a span of two years have
grown the business about tenfold.
  I'm at the point where I'm overextended - getting up at 5:00 AM to
work on computers I've taken home to work on, driving for 10+ hours
from client to client, then up until midnight working on PCs.  Seven
days a week.
  I'm making good money, but I'm getting to the point of exhaustion,
and also missing agreed deadlines for clients - from volume, not
laziness.
  Because I do such good work, my clients readily refer me to other
clients - so the business is growing, with no apparent end in sight -
but I live below my means in case the "bubble bursts."
  I'm a hair's breadth from hiring someone, but there are risks, and I
need advice on how to manage them.
  My concerns are these, but not necessarily in order:

  1. That this person will try to deal privately with my clients 
in their off hours.
  2. A lot of my clients are women, often alone while their spouses
are at work - I don't need someone who works for me, "getting the wrong
idea"
  3. I'm not sure if business will continue on the same upward
trajectory - I'd like to be able to make the arrangement temporary
at first, then once I "find my footing" with this person, perhaps
make them permanent.
 4. I also am concerned about what could happen if this person
gets hurt during the performance of their duties - I want
to protect my business and personal assets if possible.  (I have
incorporated my business in NYS as an S-Corp)
 5. Speaking of liability, I'm also worried about a situation in which
my new employee negligently damages a client's PC or loses their
data.

 I need advice on how I can proactively deal with all of the
above-mentioned potential problems and liabilities.

It sounds like you should engage someone as an independent contractor
first before you actually hire them.  All of the items you mention can
be dealt with through an appropriately worded independent contractor
agreement, e.g., non-compete clauses, damages waivers, termination by
you for convenience on 30-days' notice, indemnification provisions or
provisions which require the contractor to keep and maintain insurance
naming you as an additional insured should the contractor damage a
client's PC, etc.  Of course, a contract is only a piece of paper and
you might end up fighting to enforce it, but it's certainly better
than just up and hiring an actual employee and going naked without
~any~ contract.

I would look at hiring someone to do your running around, phone
answering stuff for you.

This person would be someone who is responsible, a good driver, etc,
and would not have the set of skills you have, and would thus not be
able to compete with you. Hire someone who is young, a good study, and
wants to make extra money working overtime. If you're lucky they'll be
able to learn from you and help you grow as you need.  If not, you're
not out a lot of money, and you made yourself more efficient by
dividing the labor correctly.

When working at your most efficient, then I would look at contracting
out other work.  Just my opinon.

I'm with dr_bob, but want to add...

Make sure you're doing your paperwork and billing as efficiently as
possible. If it takes you more than a couple minutes to bill someone,
tell me what apps you have, and I'll offer some solutions, even point
you to sample files.

Don't be a slave to your paperwork.

Also, consider looking in the yellow pages for someone JUST LIKE YOU.
See if they're slow or can handle helping you out. Don't rule out the
possibility of swallowing them up or even joining in with them. The
nice thing would be that they should already have all your concerns
covered 'cause they're already in business for themselves.

Regardless, good luck to you!

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