Wirelessly posted (Scared of sea bunnies)
Sounds like you're using 200,000kb which equates to 200MB. So your co-workers are using about 35MB.
From what I understand, emails shouldn't use up too much data. If you were doing webmail, then yes data usage would increase. Even with your extra personal emails, it shouldn't make muc of a difference, especially when you say you get 10-20 of them.
Your phone minutes do not count as data. Its counted simply as minutes used.
Unfortunately I can't comment on those apps you mention in terms of data used. But I have a feeling those may be the greatest contributors to your data usage amount.
If you're willing, might I suggest an experiment: try only to use your device for the emails and nothing else. See if that doesn't change your data amount.