Don't call to say thank you. They are busy enough. If you want to say thank you, send it via standard mail. Although it is a nice gesture, it is not necessary to send a thank you.
During the interview, some schools offer to let you come back for a day and visit the school (sitting in on classes and labs). That is a very good thing to do if you are able to do so. It will show the school you are definitely interested in their program and allow them to see your name and face one more time. It is NOT necessary to do this though. Most people are accepted without having revisited the schools.
For the most part, after the interview, just sit back and do whatever you do in your everyday lives. It is not just Texas that doesn't sen out acceptances until Dec. 1. That is the rule for all schools (I believe) - at least every school I had considered or applied to. I know all AADSAS and TMDSAS aschools follow it.
I know you want to know what is going on at all times and want to make sure they haven't forgotten you. They haven't. They just have a lot of applications to go through and a lot of interviews you give. In late Nov, they will put all the interviewed files together and determine then who makes the first cut. DON'T STRESS OUT!
