- system should let you choose the starting day of the week
This is not implemented.
- you should specify the working days of the week; should also affect reported due days (+ if you select monday-friday, you shouldn't be allowed to add task/event/etc sunday)
Due dates are specified by absolute date, so having defined work days wouldn't affect due dates. In the case of repeating events, it would be useful to be able to define events that repeat say every tuesday and thursday, but anyway this could be achived with two events that repeat weekly.
- calendar events should have a type option (meeting, birthday, phone call, etc) with small icon in calendar view and/or overview list
This is not implemented but can partially be done with tags (a tag for birthdays, one for meetings, etc) though no icon is available on the calendar, or it could be done with workspaces (one workspace for each of those properties with a different color each), though you would lose the ability to associate a meeting with a workspace, for example.
- when adding an event in calendar you should be allowed to select a period (event start/end hour)
You can choose the starting time in the weekly and daily views, by clicking at the time you want to add the event. You can't do this on the monthly view. I agree that it would be nice to have more options on the quick add.
- overview panels should have a close button (the user is asked if this is permanent or temporary change - permanent selected changes the preferences)
It would be nice. Currently you can choose which widgets you are shown on your user preferences (Account / Edit Preferences).
- it will be very interesting if we could mark the tasks/emails/files/notes/etc as important/to do/urgent + correspondent color (some default values, but also editable - like Mozilla Thunderbird, tags)
Again, not implemented but can be partially achieved with tags (you can tag an event as "important") and then filter the important ones.
- in calendar do you consider useful a Today button ?
There was a today button before, but we removed it because some people expected it to take you to the daily view of "today" and others expected it to keep the current view but take you to that date. You now have the same functionality but two clicks away, by clicking in the "Pick a date" toolbar menu and then clicking on Today.
Your ideas are very good, and of course this partial solutions I gave you aren't as usable as what you suggested, but we won't be able to implement them soon as we have already lots of work assigned for the following weeks. If you or someone you know can help us develop those functionalities you would be welcome to do so. I really wish we could quickly implement all the suggestions we are getting through this forum, because most (if not all) of them are really good and aligned with our objectives.
If you think I didn't quite understand any of your ideas please don't hesitate to clear it up.