Re: Printing dots over "a" on Macintosh
The 'u' key on a Mac keyboard does the 2 dots over any letter (umlaut?).
Hold down the OPTION key, hit 'u', then immediately let go of the option key and hit 'a' and you should get the umlaut over the a.
Similarly, OPTION + E will give you an acute over any vowel by following the same procedure.(Being able to touch-type, having to use both mac and windows keyboards and having an accent in my name, I find it easier on a mac keyboard than the standard windows one).
The only one I haven't been able to find on either a mac or a pc keyboard is the squiggly little line over the top of letters that is used in some slavonic names.