A couple months ago I noticed our water pressure get weaker when we used more than one appliance in the home. Today I picked up a replacement PRV but when I went to change them out I noticed that the lever to shut the water off to the home has some corrosion around the bolt and arm. I ran multiple faucets around the house for a few minutes and did not notice any leakage. It is rusted but doesn't seem to be at the point of interference. Should I have this replaced or am I okay for now?
That's a ball valve and they are pretty good valves. At this point, I'd just wire brush all the rust off and clean up the valve. Then test the valve to make sure it operates smoothly and totally turns off the water. If it passes the test, I'd leave it be. It's a good practice to routinely check all your valves for leakage and operation rather than wait until you need them only to find out they don't work.
The trace of white corrosion product indicates no problem at all with the valve. The zinc coating ( or less likely cadmium ) has apparently been wet, likely from condensation of humidity, and corroded. Wiping it with some oil will reduce the possibility of future corrosion. It indicates nothing about the interior functioning of the valve.
That doesn't look like corrosion to me. It looks like a small amount of (hard) water has leaked from the valve then evaporated, leaving calcium deposits. This may have occurred several times. As others have said, wipe it away and leave it alone, the valve is almost certainly fine.
I ran multiple faucets around the house for a few minutes and did not notice any leakage.
There will be pressure inside that valve whether or not you open the faucets in the house. In fact, there will be more pressure inside the valve if you do not open the faucets in the house. So, if it is not leaking now, then really there is no problem. Ball valves last a very long time.
A convenient leak detector is a bit of toilet paper. Wrap it around the place where you suspect a leak, wait, and check if there is a wet spot on the toilet paper.
Note this valve is welded to the pipe, so if you want to change it (although it doesn't seem necessary) you will need an oxyacetylene torch, which means getting a plumber.
