Both assumptions are correct. First, the nature of widgets forbids the longpress. This would be easily solved by providing a toggleable "play" button on the widget (makes more sense for ffwd, rew probably) or by using a dialog/window instead of a widget.

I haven't done this yet, as it's actually a limitation / lack of knowledge of the Apple IR protocol. Longpresses are sent by a special "repeat" signal after the real signal for which I don't know the IR code.

The same is true for the "pairing" keys - if I had all the IR codes, you could control any MacBook/Mac Mini/Apple TV even if it's paired with another remote by simply trying all 256 possible keys (and at that point we can easily do the "Mac-B-Gone" thingie, too ).