The full academic scholarships are a great deal. In fact, they are better than athletic scholarships. DS went through this process a few years ago. While somethings may have changed, the process should be generally the same. I would suggest that you contact the admissions office and ask your specific questions to someone there. Since the Citadel is a public institution, you may find answers to your questions through an internet search. What I remember from DS's experience is...
You are selected to compete for a scholarship. There were three separate boards where the prospective student could go to the school to interview and compete for a scholarship. The first board was in late fall, the middle board in December/January and the last was in Feb/March. At the time, I believe there were 25 full-ride scholarships, and many more in lesser amounts. The scholarships are not handed out equally by board. So that means, as a qualified candidate you have a better chance at the first board than the last. That being said, DS and one other student that I know of competed in the last board and received full scholarships.
Minimum standards are tricky things. It all depends on the entering class. The scholarships are weighted to SC residents, so there numbers may be a little lower than those from out of state. I want to say approx 60% are directed towards SC students, but that may be off. It has been my experience that you have more and more highly qualified students competing for limited scholarships nationwide. I don't expect the Citadel is any different. The two scholarship recipients that I know of had ACT scores over thirty and weighted GPA's in excess of 4.5. I am not saying that those scores were typical, but (like anywhere) there are some very bright student attending the Citadel.
Again, I would encourage you to contact the school. They can let you know where you stand, and if there is anything you can do to improve your chances of earning a top scholarship.