Just a summary
FINDING THE HOLES:
I always drill the first hole at my right knee height. I will sometimes mark that hole with a reflective tack, but usually I just flag the tree.
Second on left at waist height. Third on right at throat.
I measure the holes using the length from my elbow to fingertips.
The width apart is just my natural standing shoulder-width posture and just putting my elbows against the tree.
Using this system, it is always easy to find the holes or next bolt in the dark.
It is worth it to buy the power drill bit and the hand drill instead of hacking your own.
I use a small cheap Ryobi 12v to preset. I tether it with webbing girthed around the battery.
I bring an extra battery... my body gives out before the drill does.
I am Tethered while drilling and climbing. Much less effort as you can hang with your knees on the tree for leverage and you can move around more for the left side drilling.
I usually use a small shoulder bag that has a separate compartment where I keep the hand drill and spare bolts.
Spare bolts are wrapped with a ranger band/innertube to keep them quiet.
My bag is larger than it needs to be so I can easily put the bolts in and out without looking and while wearing gloves.
I pad the bag inside with a thick sock.
Another option is a Dump Pouch.
But the shoulder strap bag keeps it more stable and puts the weight on your body instead of the saddle.
When I get to height, I just hang that bag with my pack.