Rest assured, at the very least a gist of what is going here reaches their ears.
Quite. I periodically take notes to pass on and while Raze isn't on the dev team he is in direct contact with them and is conspicuous by his conspicuousness. I couldn't say how often the devs themselves take a look personally.
Occasionally they can be seen around the modding subforums but I think as with other studios and publishers, it's very rare to see them participating in general discussion for upcoming games: the mix of NDAs and fielding diverse and often enthusiastically-expressed opinions makes it a bit of a minefield.