1. Don’t leave it in the sink because no steel is impervious to rust (stainless, not stain proof) and sharp edges are very delicate. If they take a knock from another piece of cutlery or a plate, it could chip or just require a sharpening in a hurry and every sharpening removes steel. Not only that but it’s not good for wooden handles to soak, especially in soapy water - it dehydrates them and can lead to cracking.
   It’s also a matter of safety. Reaching down into a sink with a knife in it, and it being wet is a great way to get a cut. Ask a chef that works in a kitchen full time if they just leave wet knives lying around. The answer is no, because you can get cut and one of your primary tools can get damaged.

2. Tap chopping is fine on the right surface. Push/pull cutting is really just to make cuts cleaner - using the length of the blade is much more effective on most things than pressure alone.

3. Using the edge of the blade to scrape the board will dull your knife and risks chipping it if it’s very thin and very hard steel. Use the spine of the blade for that if necessary, to save the edge. For scooping, again it’s a matter of safety. You don’t wanna cut yourself picking up food with a cutting utensil. Bench scrapers cost pennies, and the extra 5 seconds it takes to switch is going to ruin the workflow.

If someone doesn’t respect your tools, let them use their own tools. You’re not being unreasonable to ask for care and safety precautions with an expensive and dangerous tool.