I'm going to explain that stuff in the "Balancing ISO, Aperture, and Shutter speed" section.
But I will reword ISO to "If leaving shutter speed and ƒ-stop the same, a higher ISO will brighten the picture"
Also, I don't think there is anything wrong with Lens Buying Addiction!
Especially if they are interchangeable with other camera bodies you may own.
Of course you don't. I don't either. It's just those who don't understand why we need all that shiny new glass.
My lenses, for the most part and within my main system all work on all of the bodies I have, film or digital. That was the nice thing about staying with Pentax. They made some awesome glass over the years. Not all of it was K-mount some are M-42 screw mount. They all work on all of my Pentax bodies up to the level of the lens. But they all get shake reduction since it's in the body. And they still make some awesome glass. Their Limited series is second to none.
One mention about p&s cameras. not sure if it's still true but when I bought my little Easyshare one annoying thing was the shutter lag. Do the newer models still have that problem? And they do take a nice picture. Look at my post with the pano in the critique thread. Done with a 5MP P&S.