Is there a way to send a newsletter to those users who share a taxonomy term in there profile
It sounds like you want something that simplenews doesnt do right out of the box. You can create newsletters (and a block for subscription links) -- but it doesnt appear to based off of Taxonomy terms directly.

Simplenews supports Rules, you could maybe define rules that achieve your goal.

I have not used simplenews, but I have a website for student surveys which has various email templates that remind students if they have additional surveys to complete, all running off of cron tasks -- you could code this type of newsletter functionality by hand without many helper modules if need be.

Sometimes manipulating a contributed module to suite your needs is harder than just doing it yourself for your project.