Okay, we don't know much about the settings for online, but of course, all cars must be equal online, we can't go with the real performances. Damage should be on of course, with collisions on as well. Hopefully F1 2010 won't have poor online collision judgment as F1:CE does. Driving aids, Traction control should be off, it would really make races interesting and the cars a bigger challenge to drive, Anti Lock Brakes should be allowed, dynamic racing line allowed, and steering and braking assists disallowed.
Like you said, race distance should be decided when the game actually comes out, but i'd love to go full distance. We also don't know anything about damage online, whether you will be retired from the race for serious damage or be reset back on track. Hopefully it's the latter, as I would not like to get knocked out on lap 1 and be forced to spectate the remainder of the race. We'll see.