i think you are not that familiar with PA so far, because more than half of your concerns are already there, and some of those are made for testing already. You can also install your custom kernel.
1. False - you can change the colors of PIE through settings>hybrid properties.....
2. Initiate PIE then slide to southwest from your point of gravity there you have your quick settings you may put the tile for network connectivity though by default it is there. But i like your suggestion especially if the signal level is with the same representation that of the battery level it is faster :)
3. The determinacy is through sliding... You know say if you have 2 notifications then 1/2 1/2, if 3 then 1/3 1/3 1/3 and so on throughout the sliding segment. But your suggestion is nice that everytime you slide for notifications there will be some sort list view that comes up especially on full screen / PIE mode, i am not using on screen buttons they eat lots of space the main reason why i am using PA is because of their PIE and its flow.
4. i think it is out of my capabilities to answer, i am not sure what are the future plans of PA with that, and i cannot picture out the essence of your suggestion for now.
5. False - just go to settings > hybrid properties then set navbar workspace to 0%
6. Color calibration of PA default kernel is brilliant :), but you may use custom kernels and you use other apps for calibrating, simple as that.