Like gladsdotter said you can still access your XP history from the left member bar by clicking on your progress bar. We got rid of the XP History and Reputation History buttons because we felt it cluttered that area too much.
It's possible but highly improbable. We have significantly increased the visibility of the leveling concept with the new member tour, as well as scattered a lot more visual queues over the last couple of months. We are also planning to add the XP and REP history links to the user drop down menu within the top bar.
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