Dave, a lot of that has to do with the type of wood you are dealing with and the method/product that you want to use. Methods that are available to a "real" shop might not work for you and me in our garage. I know that some small commercial builders send their work out for high tech finishes.
I'm not an expert on finish and it is my humble opinion that we will never get the same deep professional job that a pro will, but I've been very satisfied fumbling along with Erlewine's book. I come from an old hot rod days a hundred or so years ago when many coats of lacquer were the only way to go - that is the way I do mine now. My first two were rattle cans of nitro - the finish came out way good but I could have blown up the garage, killed all the birds in my back yard and fried a few brain cells. I then switched to a little detail gun with water based lacquer and the results are almost as good - but the method is much safer and friendlier. Even tho they are a little more expensive, I've just use the entire suite of StewMac products - they are designed for instruments and to work together. My rule of thumb for the lacquer is lots of coats, then lots more. Ninety percent goes on the floor as you sand and polish, but the only way to get a thin finish is to keep filling every void with more lacquer, then sanding most of it off.
The step the gets us all is the pore filling for woods like mahogany or rosewood. On my first couple I did one filling, expecting the lacquer to fill the rest - that didn't happen. Here is my classical with 25 or 30 coats of nitro, the little white lines are pores in the rose wood that didn't properly fill.
Now I do two or even three applications of the pore filler, then several wash coats before I start the final building.
You mention filling gaps around binding, etc. The best way to do that is to powder some of the parent wood (lets say rosewood) - as I'm sanding I put the dust in a baggie for later use. Lay a little line of the dust on your crack and wick some thin CA into it, then scrape and the line will be almost invisible. When you are doing inlay you can simply mix the dust into your epoxy and set the pearl - it will fill the little gaps nicely.
To show you how much fun you can have blundering along by yourself, my fourth build was an F5 style mandolin and Erlewine had a pretty good description of how Gibson used to do sunbursts so I figured what the heck
You can see my high tech cardboard box spray booth - one of the nice things about waterbased.
I'll add that going off to watch someone finish a guitar is apt to be a pretty time consuming thing. It takes me at least a month to lay down all the coats - I usually let it cure for at least 2 or 3 weeks before I do the polishing. Catalyzed finishes obviously changes all of that, but most small builder send it out if they want poly.
Last comment, Erlewine does have a pretty good step by step photo essay on finishing a guitar - staining, pore filling, sanding and all the finish coats. One more reason to consider his book
Those folks who brush, French polish, or use other materials will have their own recommendations - this is what has worked for me