Due to my manner of play (I like to explore a lot and do side quests while tackling the MQ in bits and pieces), I am quickly approaching the level cap of 30 while still having a decent amount of game to play.

What I'd like to know is if you still get the experience numbers displayed for kills and quest rewards even though they aren't counted towards any tally. I know I won't be gaining more levels, but I'd still like to know how much exp I would have gotten .

Nope.

See I think that would be a nice thing to have an XP stat, even if you didn't level up.

In Fallout 3 post reaching the level cap you didn't get the satisfying KACHING when you picked a lock, decimated an enemy etc. Probably just me but I wouldn't mind a statistic telling me how much XP I have gained.

There is a certain level of satisfaction you get when you hear that sound (& NV's equivalent). It also lets you know for sure when a kill has occurred. Sometimes it might not be evident if it happens far away our off-screen somewhere.