I can only add that staccato is, to a very great extent, a matter of style, particularly in later works (in baroque, it is somewhat more conventionalised, at least for organ -- where the initial idea, which can be modified, is that a staccato marking is taken to mean that the note is held for half its value, with silence for the second half). You can have a very sharp staccato -- strrike and release as fast as possible -- ranging all the way out to what I would call detache -- a just barely audible break in the legato. And the choice is influenced by the style of the piece in question and by the performer's artistic judgement. As j_menz notes, the length of the hold has nothing to do with the volume, although I'd be the first to admit that a very short pianissimo staccato takes a lot of control! It's worth working on and fiddling with.
Again, as j_menz notes, in an acoustic piano in good tune (even a small upright, although very pronounced in a good grand) exactly when one presses the sustain pedal makes a very significant difference in the sound of the note (pressing just before the hammers strike is going to be different from just after, even) and affords a degree of control over the sound quality which is very desirable (for example: find a really good grand, in tune, and play the last six bars or so of the Schubert Op.90 #1 with no pedal, then with pedal on only the last two bars...). Again, it is often a matter of style and taste. One has to have a pretty darn sophisticated digital piano to have it make any difference, though, if digital is what you are working with.