I do not know about your first question. It seems to me that you would want to wait until you finish your parasite cleanse before you do a MC, but I defer to others here.
I can tell you that I am on day 36 of my first Master-Cleanse and I had my thyroid removed years ago. I take synthyroid every day and there is NO WAY I would do this with out it. The Master-Cleanse book says no unnecessary medications. To me a thyroid replacement hormone is not only necessary, it is really just normalizing us to where everyone else is to start. I would be a mess without my thyroid hormones.
I have had a fantastic experience on my cleanse and gave felt it to be very successful.