The reflection has nothing to do with how the drop is delivered. It is simply that the main lighting must come from behind the drop, usually by reflecting the flash off the background. The colour of the background then also becomes the colour that the water shows.
Collisions are to do with two drops being released in quick succession. There is an article on the strobist site that refers to the plastic bag technique that I sent to Jonah the other day here
. By following the other links on the page you will find more info.
The use of the flashgun to record the drop is the best way. If you take a look at Kev Lewis stuff he is using a shutter speed of 1/20th and the flash output at 1/128 on two flashguns. I tend to use 1/60 and output of 1/32 or 1/64.
I did publish a link where it showed the equivalent shutter speed that reducing the flash output equates to. Try searching for your flashgun and flash duration, so SB-800 flash duration will link to a table similar to this
* 1/1050 sec. at M 1/1 (full) output
* 1/1100 sec. at M 1/2 output
* 1/2700 sec. at M 1/4 output
* 1/5900 sec. at M 1/8 output
* 1/10900 sec. at M 1/16 output
* 1/17800 sec. at M 1/32 output
* 1/32300 sec. at M 1/64 output
* 1/41600 sec. at M 1/128 output
So this means an effective speed that is much faster than can be achieved by shutter speed alone.
Not around much for next few days but as I have with Jonah I will try to answer any questions.