Re 1: From what you say, I suspect you are editing then, instead of first producing a DVD-compatible mpeg-2 (which is also compatible in terms size/length in relation to the type of DVD blank you will burn it to), you immediately jump to the burning module and use the project file there. That means the compression has to take place during the burning process, which is already a fairly complicated process in its own right.
If so, that is perfectly OK and it usually works. But over the years, quite a few users have encountered various problems with that workflow, one of the least of which is getting the compression (i.e. the bitrate) right so that your project fits on a single layer DVD. For many of us the preferred workflow is to finish editing, and before you even think about opening the burning module, you first go to Share > Create Video File and create a DVD-compatible mpeg-2 whose compression/bitrate can be properly controlled by the user. If the project is an hour or less, then you can use the default Share > Create Video File > DVD template (as long as the Field Order in it is consistent with the video in your project.) If your project is longer than an hour, then you have to vary the bitrate downwards by using Share > Create Video File > Custom. If its only 10 minutes or less over an hour, then you can simply choose a more compressed audio bitrate. But if the project is around 90 minutes, you would need to reduce the video bitrate from the default 8000 kbps down to around 6000 kbps; and if 2 hours -- 4500 kbps.
Note also that after you produce your new mpeg-2, you go to File > New Project. Don't worry about giving your new project a name. The objective is just to clear the timeline of your current project. Once that is done, you select Share > Create Disc > DVD. The burning module will open. Use the Add Media button at the top to insert your new mpeg-2 in the burning timeline. Then go to the middle of the three icons in the bottom left of the burning screen. There is a little box beside the words 'Do not convert compliant mpeg files'. Make sure that box is ticked (it usually is by default). That way, your already compliant mpeg file will not be re-encoded. Then build your menus and burn. Following this workflow, the entire burning process should take no more than about half an hour at a burning speed of 4x.
Re 2: We have been asking for this for years, with no result.
Re 3: Already there and has been for several versions now.
Re 4: See my comment on 2 above!
Incidentally, there was a compression module built into an earlier version of VS -- I think it was VS9. But it was never very good -- only really worked when the project was just a smidgin over what would fit on a DVD. So it was dropped...
Easy peasy!! 
