All good pointers, and I used each of these pointers when installing mine.
1. C-clamped the toothbar in place. Tapped teeth with hammer, made sure it was even all the way across, making contact with the buckets cutting edge.
2. scribed the hole's outline on interior of bucket. Removed toothbar and determined dead-center. Centerpunched.
3. Drilled starter hole with approx. a 1/4" bit, to maintain control. After this, you can drill it from the outside of the bucket, a little easier than wrestling with the drill from the interior of the bucket (IMHO).
4. Use washers between toothbar flange and interior of bucket, if there is any appreciable space in there. example: 2 washers on each side, etc.
It should be fairly snug in there, not super-tight, just so you aren't bowing the bucket inward as you tighten the bolts.
4a. Alternate method: weld a a piece of spacer metal on the outside of each toothbar flange if you are looking at a good amount of gap.
In other words, if there is 1/2" of gap either side, you can weld [2] 1/4" peices of flat bar (drilling and matching the hole in the tothbar flange, of course).
It's pretty straight forward, took me 15 or 20 minutes, and most of that was eyeballing the set-up.
Show us pics when it's installed!