This is very unwise. Saving PSD files before you even know if you'll edit them is just chewing up your hard drive space for no purpose. I urge you to stop this practice. Just export the web-resolution jpegs to show the client, then go back and make PSDs only of the ones they choose.
That's correct, 8-bit is enough in almost all cases. The only photos which need 16-bit are ones that you know you'll be doing quite aggressive tonal edits to in Photoshop (for example very hazy backlit photos).
Actually, as strange as it seems, the resolution is completely irrelevant. You can choose 300, or 72, or 24, or 11, or 5, it honestly doesn't matter a damn.