Measuring volatility over a period of time is the best way to catch the early part of a trend. As volatility drops the trends but you have to have a reference point, which is why you need to collect data and do some number crunching.
From what I read, Gann gave no indication of how many price units constitute one price point / time period. So angle is still pretty much subjective http://en.wikipedia.org/wiki/Gann_angles
In geometry, you cannot mix different units of a triangle to arrive at an answer. Geometric Triangles etc need to be measured distance x distance, or time x time, or weight x weight etc. You can't mix distance x time or apples with oranges. Gann was a con artist! Sleight of hand snake oil salesman in my opinion. Then there is the issue of linear vs logarithmic units of price. Either one will give you a difference in the trend line angles.
Yes, I believe EMA's are the most important indicators. I am still learning how to read it correctly. I use the momentum indicators mainly for the entry, not the exit.