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HalfPint is a trusted home cook.
what are you making? what are you trying to figure out? confused by "how much to reduce the amount of salt".
This question is incomplete and nebulous. What are you trying to brine? For how long?
About a week ago I brined a boneless center cut pork loin roast for three days before removing the roast from the brine and let it dry out for a day. I used 2 tablespoons kosher salt to 5 cups of water and I still probably could have ratched down the salinity.
There are many variables: type of meat, size of cut, duration in brine, etc. as well as what your personal tolerance of salt, none of which you bother to mention.
You will need to be much more specific in describing your specific scenario if you are to ever hope to get a relevant response.
That said, I'm not a fan of "quick brines." The salt needs to reach equilibrium throughout the entire piece of meat and that takes time. Some wet brining recipes -- particularly for larger cuts -- recommend up to a week.
I wouldn't bother with a "quick brine" but I would salt well.
Anyhow, good luck.
Okay, now I see that this is a *THREE* part question, not two.
I give up.
My suggestion is for you to omit salt in this dish.