A general note: This is only a user forum. Users of kicad try to help each other to solve problems with the current software. (And occasionally discuss ideas about the future of kicad.)
If you want to get the attention of the developers you really need to make a bug report marked as "wishlist" if it is a feature request.
Report your feature request here: https://bugs.launchpad.net/kicad
How to: http://kicad-pcb.org/help/report-a-bug/
Just a hint: The better you document your feature request the higher the chance to get the attention of developers. Also getting a lot of other people interested in your feature helps.
What helps the most is supplying a patch that adds your feature. (This means hiring a programmer that implements it or doing it yourself)
Now to your requests.
Already exists in nightly. (Will exist in v5)
There are python scripts for that.
Well i think there are plans to make drc better. But again if you need it now, you might need to make your own python scripts or help out by programming it. That's the benefit of open source. You can implement features you miss.
"Free software is a matter of liberty, not price. To understand the concept, you should think of free as in free speech, not as in free beer."
I would say: hide ratsnets of nets chosen by the user. This would allow the maximum flexibility and i don't think it is much more effort than hiding one specific net.