1. With the possible exception of a genuine scheduling screw-up, "crew rest" is always due to some other factor. In this case WX. Perhaps the better response to OP was that the problem was "crew rest caused by WX," but that's really a little over the top given that the issue is to inform OP that his flight's cancelled.

2. OP found the notification in his spam filter. That's between OP and his ISP and has nothing to do with US. He could also set up his profile for text and/or phone, but apparently hasn't.

3. The reroute OP elected is what he chose. A tad more inconvenient (72 miles), but a call OP made, not US. I presume that US would have acommodated OP on its next xDAB flight with availability.