A pause button will unfortunately never work for competitive mode, as it will be abused by those wanting to score fantastically short solve times. It may be possible to someday add it to non-competitive play, however.
An on-screen timer is a good idea and something we have on the to do list. However, it will need to be a user option as I'm sure a constantly ticking time-clock will probably annoy some people.
Hints will never be allowed in competitive play, as it would over-complicate the scoring system and probably completely invalidate the success rate competitions, but we are considering extending unlimited hints (instead of just vowels, like we do now) for non-competitive play.
Thanks for your suggestions!