For (5), if you use a theme like Soda or Phoenix and set the following in your user prefs:
The dot will be coloured as well which makes modified tabs much more obvious.
Regarding scrollbars, you can easily modify the theme yourself to get better visibility if you need it. Open the sublime-theme file for your theme and search for "scroll"; it looks like this in Soda:
// Standard vertical scroll bar
"layer0.texture": "Theme - Soda/Soda Dark/standard-scrollbar-vertical.png",
"layer0.inner_margin": [2, 6],
You can play with the other options and can edit the scrollbar png files to increase the contrast, change colour etc.
Re. (4), I presume you refer to the minimap. Configurable zoom level would be nice, but I've never felt the need for it to be any different since the point is to get a birds eye of a large part of your file, so you can see the "patterns", rather than actually have it readable. You might want to post a suggestion on sublimetext.userecho.com/ and search for "minimap" while you're there since there are some other good minimap requests too.
I agree that Sublime's status bar should definitely have more API hooks for devs including some position and layout flexibility. There's a lot of real-estate doing nothing there right now. It could show eg. line endings and encoding, clickable for easy changing; a clock would be nice (I miss that from the Brief days); option to show CWD and full file path, and some of these things clickable to copy to the clipboard or paste straight into the doc. Just some thoughts