I've only done the Oly, but that includes almost all of the sprint course
1. What time should I arrive?
if it's anything like the Oly
(probably is
), then it's first come first serve int eh racks
(by wave
). It may take time to get from the gate to transition as well. Plan ahead. they probably tell you what time to be at the gate by with your packet
(they do for the oly
)
2. Will they allow "swim socks"?
Doubt it. Water should be very warm
3. I have a road bike I've adapted for tri with base bar and clip ons and a Profile Design aero water bottle, are there any prohibitions against certain bars?
No. Just have your bar ends plugged
4. How hilly is it? What kind of gearing on your cassette are you using?
It's not flat, but there are no climbs. More like rollers. One decent little hill going each way. I use a 12/27 for the Oly, and I am a big guy and was in the big gear for all but two of the climbs. Map and elevation profile for the sprint here:
http://trail.motionbased.com/trail/activity/3624751
You can see there's not a lot of elevation gain, and the middle "hill" on the Las Pulgas out and back is more like a gradual false flat. SHould have a tailwind comig back
5. Does the total leg distance include the run to/from the beach and into the water? I'd like to know so I can estimate my time per leg.
Swim leg distances normally do not include T runs.
6. Is there any support for bike flats? Sorry if any of these questions are stupid! I'm actually sort of shocked myself about all that I don't know.
There wasn't for the Oly, I wouldn't expect it for the sprint. The roads are pretty good,try to stay away from the far shoulder, as there is some debris to watch out for, including spent shell casings 
For mixie - it's not in the basin, it's ocean swim, so I am sure there will be swim warm up time.