As for the placement of vsti's in the rack, try telling that to the bass player that only wants to stand on the left hand side of the stage at every gig!
Anyway, I understand it makes no practical difference to the outcome, but it does make a difference in using the app. With a lot of VSTi's I would need to explicitly scan down the list to pick out my strings section (which could be randomly every second item, in the above example I only have one, but other projects have many more), as opposed to logically grouping them together. The same goes for percussion, or keeping my bass in with my rhythm etc etc etc. In the above screenshot, you can see my bass is at the bottom, which irks my ***** retentive tendencies, as its away from the rest of the rhythm section and frequency wise, its at the bass. Luckily, at least my kick comes before my snare and hi-hats
The above rack is pretty reasonable as I added parts in a kind of logical order. But try to image if they were randomized! I wouldn't be able to sleep at night.
Colouring tracks/clips makes no practical difference, but all DAWs do it without question.