sorry, I’d written a reply the other day and then my browser decided to die — figured you’d have had another response by now! 😀

i’ll try to remember what I’d intended to post…

generally, I also start with 100.  and then just mouse it up and down from there, depending on what “feels” right and what sounds right, especially thinking about how I would actually drum the part (*if* I were actually a drummer… so there’s a bit of virtual virtualization going on there… :P).

and as far as things not being audible in the mix… I suppose it depends on the mix, but I definitely notice that even small things that *seem* inaudible add something to the sound… take them away and you may notice there’s *something* missing, but you may not be quite sure what it is.
(and also, the other lower-velocity hits are there because not all music is loud! :D)

in other words… it sounds like you’re doing things right. 🙂  (…as far as I know…)
you could also possibly try a volume boost and compression/limiting to make the quiet elements stand out a little more
and also, if something is *actually* getting lost in the mix, either panning or EQ should prevent it from sitting on top of something else and trying to occupy the same frequency or stereo space.