Hi Yichen
I found your notation of feather step rhythm a little difficult to follow. I think you meant "2 + 1/4 or 1/2 on slow".
i learnt to play piano when i was very young, but only took up dancing in my later years. Because of this, i'm MUCH more comfortable with counting beats, than with slows and quicks. (I'm delighted that an Andrew Sinkinson teaching tape i recently bought includes both methods - brilliant).
Can i suggest that, on the feather step as an example, you count half beats (1&2&3&4& 1&2&...etc)then it's easy to explain that with conventional timing, the right foot plants on 1 for a slow, the left on 3 for a quick, and the right on 4 for another quick. With 'rubato' timing (for want of a better description) the plants might be 1, 2&, 4. It's easy to work on this, counting as you dance, and it's not difficult to practice planting halfway between 2& and 3 (to steal just a quarter of a beat). Eventually, the idea of course is to just dance with your feelings, and forgetting the counting. But, as you so rightly said, study (and practice) are so important, and i find counting in half-beats the best way to get the feel of manipulating rhythms.