Congratulations on your decision to go pre-med!
It's a tough couple of years but I have seen many of the people I entered into school with successfully go on to medical school. They were a determined bunch who never lost focus of their goal.
As far as admissions, the higher your SAT/ACT score, the better. If you're fresh out of high school the admissions committee also looks at your GPA, the rigorousness of your classes, extracurricular actities to name a few. These criteria were true in my case, but may not be for you so be sure to check that out.
The university that I go to does take into account parents or siblings that have gone to the school. It is a private college that prides itself on graduating multiple generations in families. Although in my case there was a separate question on the application that asked if a relative ever graduated from there.
Another important thing about your SAT score is that it is typically a deciding factor in how much or what type of scholarship you will get from the school. I still kick myself for not taking the ACT over and increasing my score. I still firmly believe if I got over a 30 I would have had half of my education paid for by school-provided scholarships and awards.
Here is a good resource I used once-upon-a-time when I was a pre-med student: Student Doctor Network Forums
It's basically a forum like allnurses.com with a lot of useful information.
Good luck with everything! I have been told by countless medical school students and newbie doctors that all the med school applicants are going to have good grades but what really sets you apart is a great MCAT score and a good story to tell at your interviews.