I had a google and search on this forum, lots of topics about going to terminals at JFK you're not flying from. Seems to be by law allowed, but up to TSA staff if they let you through, and the lounges, yes you can go any star alliance when flying business, no idea about how it applies if star alliance member, presume the same. You have to go through security twice though by sounds of it as the transport between termnials is pre-security from what i can gather. Guess just allow time!