First off, I admire your dedication for trying to play this game blind.
I know there's a handful of keybinds that pair with either a unit selection or with issuing a command (right-click) to do some things. They're listed visually on icons you can click in the lower right, but the text is small enough I can't heckin read them. X and C are in there, iirc from the hotkeys in the first game, but I forget what they do.
Space pauses
Tab opens/closes the galaxy screen which can show you various information, issue commands, or change planet view
Control is used as a modifier on left/right click regarding wormholes (eg. a right click on a selection issues a move order, if that click is over a wormhole and you hold control, the move order sends the ships through the wormhole). ctrl-left click sends your camera through the wormhole.
Control can also show more tooltip information, if you're hovering over a unit or other item that generates a tooltip.
Shift will hide tooltips as well as being used to queue orders (so you can tell a fleet to move to a guard post, attack the ancillary units, and then take out the guard post, then move on to the next one.
Number keys (1, 2, 3...) will select each fleet you own (you start with one or two and can gain more later)