Different Trades, Different Contractors
I work for a major U.S. supermarket. Out of the 10 things listed above, I think we do Exchange, backup, smartphones, and HIPPA in-house (there may be consultants involved with HIPPA). All the rest are done by contractors and each contractor usually specializes in ONE of these items ... maybe two, but no more.
As for home, I had a licensed electrician wire my house w/ CAT 5 (gigabtye ethernet for home didn't seem relevant 8 years ago), and if I were to have home theater installed, I would again go with a licensed contractor. Probably a home theater specialist. If something is worth hiring out, it is worth hiring the right professionals.
