Interest on Reserves

I was just randomly wondering what the point and implications of this was today. Here are some links:

“Why is the Fed Paying Interest on Excess Reserves?”

SSRN - Interest on Reserves and Monetary Policy

Should the Fed Pay Interest on Reserves?

FRBNY - FAQs

Federal Reserve May Seek Authority to Pay Interest on Reserves

The Fed Moves Again — And Here’s What It Means

Federal Reserve wants to Pay Interest Now

Fed Announcement

(off topic, but i also remember reading somewhere about forcing privately owned banks to hold government bonds. I forgot the reasons why. I also wonder what this does for money supply (if CB buys the bonds the money supply increases. If a private investor does, it contracts (or is neutral if the government spends what is borrowed). So what's the story when a privately owned bank buys the bonds?