As far as I know the devs do read this forum site
and sometimes even post here. If there is a more direct way I don't know.
I agree with your suggestions. It would be much nicer to have separate windows for the different quest spheres.
As to the difficulty level I think that if you get a quest that means is accessible to your level (many times i have encountered quest givers that only have their shield in the head after I reached a certain level) but it could be that for some quest a group is required. As to low level... I guess maybe the tier where you get them would indicate its difficulty (more or less)