On the application form for an LLM in taxation it asks what tax courses I took. Now, I took Estates and Trusts which talked and we studied some tax principles in there. Should I include that as a tax course? Do most people?

I would give them an honest profile of you by letting them know of the courses you took in Estates/Trusts indicating they touched upon tax but not in depth. Of course, the purposew of your application for an LLM Tax is to give you expertise in this topic. I do not know what others ha ve done with their applications, but consider this to be irrelevant.