Yes, it is an achievement test and yes it is timed. If your child has an IEP or 504 plan in school you might be able to get the same accommodations he has there (if extra time is part of that). Dd11 had a 504 for some time with time accommodations due to a SID dx and she has some of the same accommodations written into her ALP now.
I'm not sure if her issues are big enough that we could legitimately ask for extra time on tests like the EXPLORE or SAT, though, and we have never sought that.
General info on EXPLORE and test centers is probably available on ACT's website:
http://www.actstudent.org/explore/ Your regional talent search may be able to help you find a testing location.
