a couple of questions about web output

As I mentioned previously, alot of this web output seems different to me. For instance, everything I created had to be CMYK or Pantone for the printshop and newspapers, an RGB would bring a job to a screeching halt.
From time to time I wonder, would I gain anything by using 4 channels of information, or would it be lost anyway when converting to RGB.
Similarly, every job had a different resolution before, but on the web it seems anything over 72 ppi is extraneous. Nevertheless I can't shake old ideas that a higher resolution would be better. Occasionally I work in 96 and 300.
From time to time I wonder, would I gain anything by using 4 channels of information, or would it be lost anyway when converting to RGB.
Similarly, every job had a different resolution before, but on the web it seems anything over 72 ppi is extraneous. Nevertheless I can't shake old ideas that a higher resolution would be better. Occasionally I work in 96 and 300.
