Hey there. I am currently on scholarship w/the Air Force. In terms of military residencies, from what people have told he, it doesn't matter if you are DO or MD. You are a military doctor and they don't make any further distinction.
In terms of Active Duty Tours, you have to do one for each year of scholarship you receive. You can either do your first ADT the June prior to school or the June right after your first year. Your first one will be Commissioned Officer Training at Maxwell AFB in Montgomery, AL. I will be going this summer because I didn't get the scholarship until mid-April last year. The three other ADTs can be done in several ways. Some people will do an actual military rotation at the very beginning of their 3rd year (sometime before the end of the fiscal year, which is the end of Sept), then do another 2 rotations during their 3rd and 4th years. This gives you the opportunity to see three different bases/hospitals, make connections, see what you like, etc. You also have the ability to do an ADT after your 2nd year in research and a few other things. After my 2nd year, I'm planning on going to the School of Aerospace Medicine Orientation Course, which usually runs for 4 weeks in June/July. I will then do one rotation my 3rd year, and one my 4th year.
I'm going to PM you the link to the website that we use for communications between the people who administer the scholarhip and the students who receive it. There is a small forum on there, but it isn't used much. If you have any further questions, please let me know. I've got tons of info, but i would have to email some of it to you.
Good luck