Sister, you ain't alone!
My brain goes faster than my fingers more often than not; and I can get very OCD about self-correcting so people won't look down on me. Sometimes I think a little madness and/or issues with self-esteem are the curse of genius.

keep your fingers on the 'home row' (index fingers on the 'f' and 'j', indicated by a raised dot or line)
and keep at it as slowly (but accurately) as need be til your fingers do catch up :)

i type over 100 wpm with 97% accuracy -- it's do-able.

I learned English as a foreign language, and have developped into a purist and snob as a consequence, although I'm mellowing. Precision in expression and breadth of vocabulary are more important to me than occasional misspellings, although if they are systematic, I do tend to wonder. It's a bit like mispronunciations - wrong pronunciations probably mean that the person learned the word through reading, but with time, they should manage to pick up the correct pronunciation.

I will differentiate, and I'll make allowances for the medium. What I'll easily overlook in high-speed written conversation, where my fingers are also constantly tripping over each other to get the words out (and where I have developped specific patterns of mistypings like 'reserach' or 'teh') I wouldn't pardon in a letter where I would expect thinking to take longer than writing, and where spell checkers are readily available - in that case, I expect the author to make the effort of proof-reading what they wrote if they expect me to spend time thinking about it.

"Do you find that you can differentiate between someone like me, and a person who is unable to really tell the difference between proper word usage, based on context, and other telling things during an online discussion? If so, does it matter to you if the person feels compelled to constantly correct themselves. Does it matter if you know that they know that you know the difference?"

Without doubt, and no, it doesn't much matter. THe difference between functional illiteracy and occasional typos (especially of the speed-induced variety) is so conspicuous that I'm carfeully not correcting my typos in this message, just to make the piont.

Thguh it pains me to do so - therel. for instance. And (ouch!) there.

The fact that a literate party knows the difference shows, whether or not it's constantly orrected. I think it's a matter of word choice and sentence construction.

Or so I fancy. (You tell me.)