Yes. The pH is strictly the mash pH. There are a couple of rules when it comes to sparging to avoid astringency: Never let the pH rise above 6 or the gravity fall below 1.01. As I mentioned, I acidify my sparge water to pH 5.4, approximately, for two reasons: I want to minimize the risk of astringency - I have a pretty good set of tastebuds so a lot of things guys in my homebrew club don't notice, I do - and I like my beers a bit on the tart side. Not sour, that's the 3.6 pH range for uncarbonated, finished beer, but tart, at or below pH 4.4. Routine batch sparging never raises the pH or lowers the gravity above/below the critical points, so unless your water is way out there, there's no real need to acidify the sparge. I just like the risk reduction aspect.
You can choose whether to add salts to the mash, to the entire water volume, in the kettle, it all depends on the outcome you want. I recently did a Yuengling clone and, side-by-side with the original, discovered my water wasn't "minerally" enough. Next batch, more gypsum added in such a way it becomes part of the flavor profile, not just to control residual alkalinity. Key there is I know why I'm doing it. Water chemistry is a refinement step, kind of like that final pinch of salt in a recipe. For now, keep your mash pH around 5.4, acidify your sparge water to 5.6 or below and be sure to dechlorinate. You'll learn the "why" later, and can make more informed decisions about how to treat your water.