Khaled (and Anil):
You have identified one of the significant bugs with the spell checker, namely the inability for it to retain the ability to ignore mixed case words. This minor issue is enough to render the spell checker almost useless because of the high number of words that fit this description.
The use of "Tall man" font which is mandated for medications means that many medications (e.g. predNISONE) will ALWAYS be incorrectly recognized as a misspelling. By the time you have "spell checked" the medication list, you have already had to make a number of unnecessary clicks...and you must do it every time you re-do the note.
Anil, I think this explains your numbers 2 and 3 above, as it is likely happening with other names (e.g. McMahon) or if your secretary has a mixed case user name (showing up in the allergy section).
This is a relatively minor issue, but the total cost in time wasted to all AC users is significant (either you waste time re-"ignoring" words over and over, or use don't use spell check and lose the utility altogether). How hard is this to fix? I have no idea (though a switch to an entirely different spell-check product couldn't be that hard). I feel that it is disrespectful of AC users that the company has ignored the complaints about this bug (and others like it) for so long. We know that they have been aware of it for years but we have no evidence that a fix is even on their radar.