1) The wire will be run into the house somehow. It depends on where your walls/floors are and what kind of interior damage would be done (if any--i.e., unfinished basement) in each possible location.

2) Your electrician can put a twin breaker in a single slot if you need the space.

ok great thank you.

If the electrician is using direct bury cable, the cable needs to still be protected from physical harm where it is exposed. He will probably put the cable into PVC conduit running from the bottom of the trench up along the side of the building and into an LB fitting, which passes into and through the wall of the building. If the cable is out of harm's way inside the building then the cable can run unprotected right into the panel. Also, the circuit running outside to the lamp post must be GFCI protected. He won't be able to install a GFCI breaker in a single panel slot. It will need a double slot. His alternative would be to hardwire a GFCI receptacle out at the lamp post with the lamp plugged into the receptacle. If that is not code allowed in your jurisdiction then he will have to install a subpanel near the main panel with a GFCI breaker.

Thanks bigbird, there just might be more to this than meets the eye, thanks for the insight.

Is there anything terrible about placing the outdoor light downstream of an existing GFI outlet or installing one to avoid the expense of a GFI breaker? Is this against code? Assuming all other work is properly done and the line tapped into is not overloaded. If against code, is there a particular reason? Thanks!