Also the OLSAT is screener - your district/school probably only uses it to screen. The kids that "pass" the olsat are still not considered identified as gifted - they go on to have a proper evaluation with an instrument like the WISC or SBV. It is not uncommon for a child to pass the OLSAT but then not be identified ultimately as gifted and vice versa.
Not necessarily. My district uses it as one of the 3 different ways you could qualify as Gifted. You could also go to a psychologist for an evaluation, or test very high on the standard state testing. My son tested very high on the OLSAT in 3rd grade.
Do get testing by a pscyologist, look for someone who is good with gifted kids. Perhaps your school district will have a list of psychologists as a place to start.