re: "Can I use pex and crimps to attach a new outside faucet to my copper on my house:?"
For connecting to copper, you need to use the Sharkbyte type fitting rated for copper (gatorbyte at Lowe's) or the Quest fittings at your local hardware. Those will work on both copper and pex.
I am curious about the obsession with crimping pipe connectors. Crimping is OK if you are in the business and do enough to warrant the tools and training required to do it right. For smaller jobs, like re-plumbing an Airstream, there are other solutions that don't require the capital investment, are less prone to error, and much more convenient.
interesting note about O-rings only lasting a few years ... many modern faucets use those things and have lifetime warranties.
Then there's the polybutyl pipe, acetyl fittings, and aluminum crimp ring story - you'll find these on early 90's rigs and the odds are you will find they need replacing (Shell lost a big lawsuit on this).
As for each of use, cost, and 'professional' look, as well as simple construction (no O-rings!), possibility of re-use, and capability to tighten if need be, I still prefer Flair-it fittings on pex.