Thing about CSGO is that the majority of people playing it have mediocre PCs that will probably explode with Source 2. I'm all up for it, but I'm perfectly happy the way it is right now.
1446 hours, not a lot that stands out as well although I've logged 100 more hours on my top played game.
CSGO - 332.7h
TF2 - 201.3h
Path of Exile - 140.5h
Have a couple of games with 100 hours, then it goes down from there.
No one knows for sure, but I read this guide which says MVPs count a lot. Also it has an ELO system, if the other team has higher ranks than you, you get more ELO for winning, they get less for winning etc.
Agreed, I'd rather have longer potion durations like in the 1st and 2nd than having 10-30s long potion durations which can stock up everytime you meditate.