I see very nice ideas and news.
Regarding ranks, I agree that it's better to keep them simple. Four or five ranks, not more, and all must be quite different.
Private/Rookie
Sergeant/Squad Leader
Lieutenant
Captain
Commander/Colonel (make this one very rare, why not unique ?)
Regarding "medals", I don't know how you wish to implement them yet, but I think it's a very good idea. Even if they do not give any bonus to the soldiers, it allows to give them a character and a story. What I'd really like to see implemented is a little file for each soldier. For example, a soldier right now has a name, a rank and a set of variables reflecting his abilities. Maybe, adding a little zone where we can input some text could add to the atmosphere.
Or an editable log: "On April 23rd, 2084, was promoted to Sergeant after killing 3 aliens during a dangerous mission. On June 2nd, 2084, was awarded Earth Defence Medal for Heroism on the field. On June 5th, 2084, was heavily wounded during a mission, transfered to hospital for a 16 days healing period."
On the other hand, I do not know how hard such a thing could be to code...
Malick