Kakashi isn't an Uchiha, and therefore the Sharingan takes more of a toll on his body than it would if he actually were an Uchiha - Thought this was common sense? -.-"
Itachi keeping his Sharingan active would have the smallest chakra drain, it's completely irrelevant.
Now, people say Itachi has low Chakra reserves because of his fight with Sasuke. The common misconception people like you have is when you state a "prime" Itachi or a "healthy" Itachi - Simply because, there's no such thing. Itachi died at a relatively young age, so we don't actually know whether he was in his "prime state" or not - And if he was, then we saw his "prime state" against Sasuke.
The greatest flaw that your entire argument has is the listing the techniques themselves, simply because we don't know how much Chakra each of them drains specifically... So listing a few feats he did during the fight isn't very useful at all. Now, don't get me wrong - I'm not saying he has a low Chakra reserve... But the fact remains that his chakra reserve doesn't appear to be as high as many of the other characters we've seen because of his illness and with Itachi, you can't have Itachi without the illness because then it's no longer Itachi.