You're making most of those problems too complicated. You can solve a lot of thing by just doing the exact same analogue of what the actual game does:
Important announcement: drops all pins to the floor and have the message raise in braille in the middle until acknowledged. Like normal game, basically.
Find nearest creature (like the V key normally): The nearest one that it is selecting at the moment just has its glyph flash (i.e. drop to zero, then reraise, drop to zero, re-raise) which makes it very easy to locate if, while reading the info off to the side, you see it's the one you want. Same goes for buildings, etc. Also, the actual sound of the pins "flashing" adds a second sensory cue to the location, without even havign to build anything special into the system at all. Merely a happy side effect.
Tracking a creature: Already a vanilla game feature that translates just fine: use hotkeys follow creature option. Now you just hit the hotkey and ta da, the display centers right on them (lots of ways to make center tile special and easily found which should probably be in place anyway. Simmilar to the little nub on the "5" key on most cellphones. Cheapest would be to just have the center glyph use pins made out of a unique material, as long as materials aren't overly used elsewhere).
If you want, give an option to either recenter or just make the relevant dwarf flash (you'd want the former in most cases, the latter in cases like directing a whole squad of military)
Also, what method is this going to use for detecting the tactile input of the user's hand? Pressure? Proximity Detecting laser grid?
Yes pressure. Pressure sensors are robust, unambiguous, and cheap. You don't even need to have a sensor/button for every glyph if you combine it with another dirt cheap mechanism like capacitance to see where your fingers are, and use staggered sensors and stuff.
But probably a pressure button for each individual glyph even would pale in cost to the pin mechanisms anyway, so whatever. Just a switch for each one.