Rpm increasing when braking

Hello, I'm seeing a couple different symptoms that I'd like to share thoughts on separately. First, if the engine speed increases when hitting your brakes in heavy traffic, consider that there could be a vacuum related concern, because engine speed and engine vacuum are related. The brake booster requires engine vacuum to provide power assist. There could be a hose leak for a booster issue. Regarding the grinding noise when reversing, very difficult to determine based off of the description of the concern. Is there a possibility that your new brake components are dragging? It's very difficult to know without hands on inspection. I'd recommend a good inspection by a local shop to see what you are experiencing firsthand. https://repairpal.com/auto-repair-near-me