Hi Gene,
Good questions – no simple answers unfortunately. Target hydration depends on the desired dough feel and the desired outcome…e.g. you don’t want a wet challah dough that you need to braid, but you do want a wet ciabatta dough that is shaped very simply and is meant to be airy.
The amount of whole grain flour in the dough, type of wheat flour, and seeds and berries will impact how much water is needed to get a particular “feel.”
Some rough targets I tend to hit on artisan-style breads are:
refined flour: low to mid-70s
under 50% whole grain flour: mid-70s-low 80s
up to 100% whole grain flour: 80s-100% depending on the wheat variety
Soft wheats can be as low absorbency as refined flour.
I can’t really speak to your starter feeding protocol, only to say that if it works well for you, then it’s perfect. When using a thick starter in a recipe calling for 100% hydration starter, you can use a little more water.
Most recipes with additional wet ingredients calculate them separately from the water e.g. pizza has olive oil and it gets its own line in the baker’s percentage table.
The bulk is stopped when the dough has expanded and become webby. For some dough, doubling works, and for others, that may be too much. How much you handle the dough can also mask doubling, which I explain a bit here.
It’s also important to factor in what kind of final proof you are planning. I tend to bulk far and final proof less. This is just habit. Other people have fantastic outcomes with a different approach: bulk less, final proof more aggressively.
I hope this helps and that other people in the Breadtopia community share their hydration and bulk fermentation strategies.