I never implied Sakura has low chakra, remember her battle against Sasori, It was one of the longest battle that ever occured in the manga. And as Chiyo stated all of her techniques (dodgin, enhanced chakra strength and healing) all use a lot of chakra.
I just said that Tsunade has more chakra because she can seal a lot of chakra away after that diamond.
Also have to remember Tsunade is the Grandaughter of the first Hokage, and the original Nine tailed Jinchuruki, her chakra reserves are probably one of the highest in the Manga, afterall if she could feed it to the Konoha Ninja force during the Pain invasion.
Sakura as far as we know does not have the same heritage as Tsunade, so she'd need to work harder on getting her reserves up, and it's unlikely she'd get it to the levels of Tsunade, who's related to two of the three strongest clans in history, and a direct decendant of the Sage of six path.
Kiba vs Sakura? Interesting matchup, I have no idea how strong either have gotten recently so it could go either way, it would definitely be a physical fight, and probably also use Chakra pills, I think Sakura might edge this one, she's much smarter of the two, would make better use of her chakra, and considering Kiba relys heavily on his motor skills for his whirlwind attack, as well as his keep sense of smell, i'm sure Sakura has by now learnt that Electric attack Tsunade used on Kabuto that messed up his motor skills, and also knows allot about poisons, so she can take away Kiba's two biggest strengths turning the match into her advantage.
So i'd give the fight to Sakura.