That sounds cool!
I don't mind replaying levels especially if the guys could be standing in different placements and facing different ways each time... That would maybe be cool as well!
I won't be adding much randomization, mostly to make sure that the playthrough is equal for everybody.
That being said, I have planned to add a set of (very) difficult challenges which unlock some very fun (secret) stuff.
Depending on how development goes, I might even add some bonus content. This can be compared to CoD WaW its extra zombie mode. However, I can't make any promises yet!