In the morning it’s typically in the range of 2500-2600.
I’m more after filling my chest by doing revenge. That’s easier, but only gets me 20 cups each, so I stop at 2700-2750. … repeat cycle
If I’m lucky to wake up to 2700 I go for a short sneak peak into top 10 
Is there sth like a max troop level?
Or should we buy 1000s of them to reach 4,5k teampower someday?
If yes, what was the highest troop level ever seen?
Max troop level = 30
Cup Floor is usually 2550-2600
“long periods” 
My experience is that when I hit 2750 or especially if I hit top 100, when I log out for 5-10 minutes I get hit a dozen times immediately.
Which makes sense. I try to reroll for matches that give me more cups than I lose. If I’m at say, 2700 cups … there are several thousand below me (fail that test) and only a couple hundred above me. If even only 1/10 of the players re-roll for a good cup return, anybody with high cups will get hit a LOT…until their cups drop so they don’t qualify anymore.
2700 definitely seems to be a threshold. Can stay around 2680, but at 2700 you 250 cups in ten minutes every time. Usually stay in the 2500 range without any trouble.
2550 to 2600 seems to be the normal range for me.