Windshield bolts, that sandwich the shield between the inner and outer brackets is 6mm. Not sure of the thread pitch. Depending on which one it is, they are 3 different lengths if I remember right.
The bolt that holds the rear of the passenger seat down is also 6mm. (6x20)
For bolts that are visible, like you are referring to, I usually order them from Honda. They are shiny chrome, and match the rest of the bolts. They cost a few bucks each, which is more than they cost at the hardware store, but they aren't THAT expensive in the end.
If you want a reference, go to
http://www.hdlparts.com and use the parts finder to look at the microfiche for exact parts....and part numbers.
-Scott