Your first is so wrong. You clearly can't do math. If Chopper used Monster Poin before 1010 where Luffy started to fight 1v1 with Kaido and now on 1014 he has less than 10 minutes of the original 30 minutes. That means Luffy vs Kaido last less then 20 minutes.
About your second, you are completely right. But... We could guess that right at the end of WCI arc because Luffy was told to be Gonkou while Marco didn't took WB's place as Yonko.
So Luffy with a bounty of 1,5 bi being a Gonkou and Marco not a Yonko or even a Gonkou would explain why Luffy's bounty is greater than Marco. But well noticed by you, I just think about my explanation because of your observation.