Don't worry, we made this up. You're not that behind the times. We would describe this an an approximately semi-formal event. Have fun with it and be as fancy as you want to, or just wear something you think you'll be comfortable in. Ideally, don't show up in jeans and a T-shirt, but we probably won't kick you out if you do. Probably.
Your guess is as good as ours. Since it's going to be January in central Texas, the weather will be anywhere from 30 to 80 degrees.
This is Texas. That's not going to happen.
The wedding will go on, rain or shine! The Wildflower Barn offers a number of covered areas and heaters, so the weather won't make a significant impact one way or the other.
Absolutely! Just please let us know a reasonable amount time before, to make sure we have enough space and/or food.
Harare, but I hardly see how that's relevant right now.