extracting parts of text for the purposes of new date fields

I suggest this approach although I'm traveling now and can't write out the whole formula for you.  You will need the Mid function similar to Excel to parse out the text into their respective YYYY MM DD and then use the Date(YYYY,MM,DD) function to make a date field.

Date(

ToNumber(Mid([My Field], 1, 4)),

ToNumber(Mid([My Field], 5, 2)),

ToNumber(Mid([My Field], 7, 2)))

then similar for the next date field but stating off at position 10