1. I still can't see the difference between using manual mode and simply dialing exposure compensation. Unless of course you want to do without the light meter altogether.
I do find 'spot metering' useful in some situations -- you don't have to guess what the light meter measured.
2. Using the histogram for exposure is nice but be careful of cameras that do not provide separate RGB histograms. Many times only one channel is saturated and you can't see that on the combined histogram.