It also works for dropping things without their hotkey.
Just drop them as you normally would, but press a number before you mark them, if it works the item will be marked with “#” instead of “+” unless the number you entered was greater than the amount you have.
The game also accepts input of numbers with more than one digit, and will mark all of a stack if you input a number greater than you have.
Alternatively, you can use Advanced Inventory Management (default key “/” on the experimental builds), it’s a lot more dynamic, but until you’re familiar with it , it might be confusing. Advanced Inventory Management is the one that lets you move specified amounts of items by pressing “m”.
As for weapon techniques, they are automatic, the likelihood of using one is dependent on the skill with the associated weapon. If one is used it will show up in the text (e.g.: rather than "You impaled the zombie for xx damage, it will read “You displace and counter the zombie for xx damage”) In most cases the only noticeable difference without paying attention to the text will be attacks knocking zombies back or hitting two or more at once, and of course increases (sometimes major) in damage. Take note of the weapon you’re using, though. Not all weapons are compatible with all styles. You can check techniques, and compatible weapons for a style by opening the style select menu (the default key is “_”), highlighting the style you want to check, then pressing “?”.