This is Why the Monolith is Taking So Long

I would probably just apply "Distance Doesn't Work" literally for ranged spells and missile weapons. The players can still cast and fire all they want but it will never help them out. Touch range spells and cast on self can work as normal.  It can appear that the spell or arrow is flying through the air as normal but it never arrives at its target, the destination, just as with player movement.  And, I would say there is no real way around this.

Of course being inanimate objects or magical energy and not sentient beings with eyes, this makes the blindfold solution to player movement sort of strange.  If anything, I would keep the movement restrictions with regard to all and figure out another possible way to allow the characters to move.  Whether this same method could apply to the spells or weapons would
remain to be seen.

It just seems much more fun to hamstring all the movement and range combat in a way to make the players really think, instead of the simple blindfold to pass trick.

As far as speaking goes, I would allow it given if the players are within touch range, since the sound waves don't really travel to their destinations either.  It's a cheat but otherwise lack of communication could become a crippling pain, and will be if they move apart.

Where this theory leaves light and it's travel time to the eye in order to view the landscape, though is another matter entirely.  I can see your dilemma here James.