Well that was fun :)
Honestly - I'm having the time of my life with all of this, and the farrier visit was another education. All the advice above was so helpful, and did give me a good mental picture of what was going to happen. The farrier was great and told me to stand exactly where some others had said to hold her - My girl was very good, though I did need to be firm a few times (which was good reinforcement for both of us anyway). No big drama thankfully. It was an unseasonably cool slightly breezy morning, so flies were a non-issue. I can see where that would definitely add a level of complexity.
He was the type that was quiet and focused while he worked, but stood and talked with us for quite a while afterwards. Apparently my friend has worked with him many times. Thanks everyone!