I have a hard time keeping to the playstyle my character is meant to use in roleplay. Mainly I stat a spy but 99% of the time I end up running and gunning like John Rambo. Since it works and is much quicker I don't see much reason NOT to do so. This, plus a lack of mercenarial espionage-type missions, saps my roleplay of a lot of its, you know, role. I'm at a loss on how to address this issue so I'm asking for suggestions.

The second part of my roleplay that quickly falls by the wayside is my character is supposed to be a med-x junky, primarily as an escape the trauma and psychological damage a life of a post-apocalyptic infiltrator would no-doubt accrue. However I have little idea how to play the junky type nor the psychological damage. I'd like to here any suggestions you could give on these too.

As to the second part, just use Med-x until you are addicted. Then you have to deal with the constant search for more, suffering Agility(-1) and Intelligence(-1) when you run out. Get the Stealth Suit Mk2 from OWB, as it automatically injects Med-x when your health drops low enough. I would imagine you would be prone to stealing from doctors and anyone else who has some Med-x.

As for a spy, use silenced weapons, build up Unarmed and Melee skills so you can take all the ninja-type perks that would apply to them, like Mr. Sandman for silent kills. If you want to support the Legion you can play as a Frumentarius, doing a lot of sneaky stuff while outwardly passing as a member of another faction. Female Legion supporter(Speculatore or something) would be the deepest cover of all, I would think.

Or imagine you're a spy for the NCR - they have the most quests so you can pick and choose. Pick a certain spy you have in mind - James Bond, Ethan Hunt etc as use that as a starting point.

I always go independant, hurray for backstabbing! The character is mostly based on Daniel Craig's James Bond (particularly Casino Royale, the newer one not the old comedy) though with more real-world espionage added.

Equipment (I prefer the Assassin's Suit in Dead Money anyway, doesn't waste stimpaks/med-x) I've got covered, the main problem I'm finding is that it's ultimately pointless and counter-productive to even try being all sneaky-sneaky and the game doesn't react at all.