Lots of good advice already posted.  Here are some observations from
my experience, but there are a lot of ways to get to the endpoint you
want that also work just fine.

I used to make a lot of flint strikers out of old horse drawn hay rake
tines, worn out files, etc. which I believe is the equivalent of O1.
The most important part is to get to the non-magnetic temperature and
let it soak at that temperature for 2-3 minutes to give time for the
phase shift to complete.

I have quenched in several kinds of oil.  Used motor oil works, but
leaves a dark surface that can be tough to polish off.  I have used
whatever cooking oil was unguarded in the kitchen in a pinch.  I had a
portable setup so did this outside and did not have to worry much
about fire, but do have something to smother a fire as others have
noted.

I used to temper strikers spread out on a pizza pan in the kitchen
oven.  Use a good oven thermometer.  Preheat oven to 375 (preheat so
it does not get too hot) and put them in the oven.  After an hour,
turn off the oven and go to bed and they were good to go the next
morning.  QC was to drop one on the wood floor.  If it did not break,
it passed.  This turned out to be a lot easier than doing them by eye
over the forge, and more consistent.  Plus I could do a dozen or more
at a time.

Propane torch will do the job for smaller items.  I made some
inletting chisels once out of concrete nails and propane did the job.
I dropped one hardened chisel on a wooden floor and it broke.  Those
that were tempered worked fine.  Maybe not the best in the world, but
what do you want for something that cost 5 cents.  

Good luck and have fun.  I will have my forge back in service by early
August after far, far too long.  Really looking forward to get back to
it.