Answering my own question:
No spec to be found. I used the ratchet with the shortest handle I had, so as to not be able to over-torque and strip the threads. It's still possible if you have a strong grip but the small ratchet makes it "safer."
The bolts are 12mm.
Finding the right O-rings is challenging. I used some that were a bit larger, and ended up having to lightly tap in the hose ends to get them onto the fittings. I greased the O-rings before installing the hose onto the fittings.
I went as tight as I dared, then had a friend with the proper kit pull a vacuum on the system. After we were sure it was all OK, we re-filled. The volume of refrigerant necessary is on a sticker on the car itself. Pull a vacuum, it is needed because the system has been exposed to atmosphere. We used a scale upon which we placed the canister with R134a, and so we could measure the weight of the refrigerant as it was leaving the canister and entering the car -- the canister got lighter so we knew when to stop.
So far, so good.
When we were done, at roughly 25C ambient temp my low side pressure was around 20 PSI, my high side pressure around 220 PSI.
A/C was always a mystery to me and I hope this helps someone.