If it's all true, it sounds quite unprofessional. Are you learning stuff, though? Enough to put up with a bunch of politics and unprofessional behaviour? Is the training and atmosphere otherwise good? Or not?
In the end it's basically your decision: for you, do the pros of continuing to train there outweigh the cons, or not.
Personally I would be inclined to just roll my eyes at the promotion politics and otherwise ignore it, but this would be the much bigger deal to me:
some one who's been verbally abusive, arrogant, and over-all have ego trips at junior's expenses.
But everyone has different feelings for which things they can put up with and which they can't. There's not necessarily a 'right answer' - it's a personal decision for you.
(Incidentally, your math doesn't add up -- there are only 365 days in a year. But whatever, a typo, we get the general idea)