As for the armor:
I don't either look easily on 21th century equipment in the Cyrodil, however, I don't close the idea of using some features of modern armors, such as using only small pieces of body conformable armor to allow more swift movement, however made to look more rough. Same goes with utility belts etc. the idea may be used, but as more impended to fit the Cyrodill.
The weight of armor should be more of suggested to fit better for the task; if it's full blood sneaking, an armor may not even be needed, but if you are supposed to encounter powerful enemies, even a heavy armor may be suggested.
As for the storyline:
It occurred to me that there could be actually two ways of getting in to the group, the choosing by skill, or choosing by infamy. The choosing by skill would be maybe even automatic after you've become the "champion of Cyrodil", and the instance running the show realizes that most of the saving was trough your skill (this could maybe "require" that you are of certain level of sneaking and marksman and infamy below value x), and you'd be approached by the member of the OPS.
The choosing by infamy could be based on getting in jail after the main quest (with the value of infamy over, or equal to x), when you are not actually sent to jail, but to a strange questioning.
At both cases one could say either yes or no, and the difference between these would be the person approaching you. Yes in this phase I introduce you the idea of two sources of missions under the same faculty (that offer in a way or another different nature of missions, as killing "known evil" critters or killing "nobility plotting against empire"), that could maybe later on lead to the conflict between these two, where you would be caught in the middle and would be "forced" to "choose a side" (or choose your own personal benefit over their). However I don't believe that, except for the last task, you could go trough both "leader's", or "mentor's" or whatever they are called, quests without missing any. As for the last, the outcome would be up to you.
So that imfamy thing... you mean like you get taken to jail... then the black ops takes you to a meeting for a chance to redeem yourself? sounds alright to me!

but that utility belt thing... that's making me think the armor is going to start to look like this...(well if we use the sneaking gear that is...)