protein sequencing from a western blot

[lw75]

Hi there!
I am interested in learning more about protein sequencing from western blots.

1.  is this method reliable?  How much protein is required for successful
sequencing?
2. can it be done from an SDS-PAGE gel as well as a native PAGE
blot?
3. does anyone know of any companies with the sequencing apparatus that will
process the samples for you?

Any references would be appreciated!

Thanks!
Lynne Whitehead