Life After Voldemort

I got to thinking and a couple of (Brainfart) thoughts popped into my head about the Harry Potter series that I needed to get off my chest.  First, after the final epic battle and (spoiler alert) with Voldemort dead, did Harry, Hermoine, and Ron have to go and finish their last year at Hogwarts?  Seriously, those three were the most responsible for helping rid the Wizarding World of Wizard Hitler, but they did so by skipping their final year of school.  So, were they required to go back and finish their final year of Potions and Defense Against the Dark Arts and whatever other stupid courses they take or did Hogwarts reward them with honorary degrees because they sort of proved that they know their shit by killing Voldemort?  And for that matter, every other student at Hogwarts is probably going to be held back due to the fact that their most recent year at school was marred by the tragedy that happened at the school and because half of their teachers were Death Eaters who were teaching them propaganda against the good guys.  In other words, their education wasn't exactly up to par their last year at school and they are probably going to have to do it all over again.

Next, why exactly was Ron's dad so confused about Muggles and their technology?  Didn't he work for the Ministry of Magic?  You know, the place that is located in downtown London and the place that he has to walk past a couple hundred of Muggles everyday just to go to work.  So, why is he always asking Harry about telephones and whatnot when he could just as easily watch a random bloke use one while he is on his lunch break and learn everything there is to know about it?

And lastly, does anyone else find it strange that the Wizarding World celebrates Christmas when the fact that being a wizard is basically like spitting in God's eye?  Or do they celebrate Christmas because they actually represent a species that is truly a copy of God's image?  You know, being a magic being that can create shit out of mid-air.  I always found it a little strange as to why wizards didn't have their own holidays, something cool like "Happy Dragon's Day" when everyone rides around on dragons for the hell of it.

"I killed Voldemort and they are making me take this bullshit anyways?  I should start an army and teach these people a lesson about who I truly am!"
"Um, Harry, that sounds a little like what you just stopped by killing Voldemort."
"Whatever, anything to get out of this stupid class."