The stored Slash and Cross Step is visible in Katana's resource bar, with red for Slash and blue for Cross Step. Newer skill uses enter from the right. Using Kendo, as well as dying, resets the counter.
Thousand Cuts allow Katana to effectively turret dive.
Not only does Thousand Cuts avoid retaliation (including turrets) for the duration, it resets turret targeting upon use. If you kill your opponent with Thousand Cuts, the turret will not target you when it ends as long as their are ally minions for it to target nearby.