M.net hardtop FAQ has been pretty handy for me. Take a peek at this link as re: part numbers and such...
http://www.miata.net/garage/hardtop/#99/99
I know that there are persons who choose, for one reason or another, to not use the side latches (top didn't come with any, non-hardtop rollbar, et al.). I'd personally not feel the top to be very secure without them, but that's just me.
Should you be interested in using the side latches at some point, when I ordered my striker plates, they came with the needed bolts. Don't know if that's just a Trussville thing, but thought it might be handy to know.