1 Yes. But not like Illustrator, etc, which are text-handling tools, which are not drawing tools. You need to learn the shortcuts in the drawing tool.
1.a In any standard program on an Apple, Command-t will open the standard Apple Text palette (Command-Shift-c will get the colour palette, etc). As long as the text (entire ribbon or partial) you want is selected, whatever you do in the palette will affect the chosen text.
1.b Command-Shift-= (Command-+) and Command-.
2.a Yes but don't. Illustrator is very non-standard, so you are (perfect example here) locked into the non-standard shortcuts. Learn the Apple shortcuts, they work on all standard programs (but not on non-standard programs).
2.b To change the keyboard shortcuts (if you must), go to the Apple menu/System Prefs/Keyboard/Keyboard Shortcuts. It is a different world over here. Read the help (the question mark). Do NOT change the Global or common shortcuts, go to the bottom of the window and choose either ApplicationKeyboardShortcuts or AllApplications. Add a shortcut (the plus sign). Choose the app you want; the Menu/<action>; and the shortcut.
3 Yes.
3.a Play around with the margins (figuring it out for yourself is easy enough), so that your PDF will be rendered the way you want on the target machine. Eg. Adobe Acrobat has weird margins, and renders a doc with difference margins by automatically scaling it down: If I set up a doc that renders perfectly in Preview, on a Piece of Crap using Acrobat, it will show up as 97% size.
3.b Not only that but (along the same lines) how the page will be rendered on the [unknown] target computer. Get the Text palette up, and choose the PDF Collection. Those fonts are safe.
3.c OG will let you create quite complex diagrams (layers, etc) which Preview can handle, but Acrobat can't.
4 I certainly do not have that problem on 4.x. Are you sure you set the UnitOfMeasure at the top of the window, just under the Toolbar, above the ruler ?
What exactly is "Arrangements Separation Palette" ? I have limited access to 5.x, I do not have it at hand, but I do not recall it there either. Can't find it in the manual. Do you mean Diagram Layout Inspector ? Anyway, if it has that inconsistency, it is a bug, mail to <omnigraffle@omnigroup.com>.
Google is for fourth graders who need help with their homework. Wiki is for stupid fourth graders. You need to go to the source if you want relevant info on anything.
Cheers