Snowden claims that encryption works, and I have no reason not to believe him on that. There definitely is significant amount of people doing crypto research who are not (directly) affiliated with NSA, I'd suspect that they all collectively can not either have missed any intentional backdoors or been bought off by NSA.
Yes, if you have nothing of interest for the NSA. Otherwise almost every encryption could be subverted with an access to the servers and soldering gun - you just touch the body of the guy that has knowledge of the keys on the (im)proper places with it.