Congrats on running Tink, I was there too.  I ran the 5k race at Coaster Run last year, may not run it this year as I signed up to do the 10k race portion of the Great Race of Agoura the day before.  It was fun running around the other theme park and happy I got a picture taken with Snoopy.  The atmosphere was a fun one and the slice of boysenberry pie at the end of the race was quite tasty.  Any ways, glad you finished Tink without really training for it.  I don't recommend that to anyone as it would be better to have a plan going in to the race.  The Coaster Run is a flat course, with only a short downhill and uphill as the course goes underneath Beach Blvd.  Unless you have a specific time in mind in which you want to complete this race, you should have no problem completing it as you have done a half.  Training for it will help you achieve a specific time.  The 10K I am running is a hilly course so I will have to get in some hill training, especially hill intervals, as well as maybe a couple of long runs with similar inclines and declines.  I make sure that I will not eat anything the day of, and the days leading up to, the race day that may cause my stomach to misbehave.  Good luck with your running and enjoy the race. Maybe I'll sign up to run the 5k again, it'll depend on my training for the race I've signed up already.