I'd say not to focus on HH/HI specially and don't wait for it, it can vary on whether you experience it or not and which type of it, WILD is just about falling asleep while keeping awareness and it is not a waiting game, waiting for something will more likely to keep one too awake. But other than that, in case you do experience HH this thread has some tips on how to possible use it for WILD entry: http://www.dreamviews.com/wake-initi...ntry-wild.html
As for questions, for first one, HH varies from person to person and sometimes even from attempt to attempt, so it can vary how it interacts with visualization, as for the second question, time is irrelevant because WILD is not a waiting game and some level of time contraction or dilation is possible through NREM, so it's not something to be focusing on, but if you can't manage to fall asleep for an hour or something like that then you are most likely too awake, in that case try doing less activity and/or experiment with WBTB times.