Always use knives for their intended purpose unless you just have amazing knife skills and can pull it off. Generally if you think you shouldn’t do something with your knife don’t. Coconuts and the center of bones will win a fight with your Japanese knife most likely, don’t do it.
Scraping food with the edge of the knife as well as holding down the center of the spine and ‘chopping’ causing the knife to torque will damage the edge where it is being twisted.
Carbon steels are a variety of steels with a chromium content less than 13%, the reactivity or rate at which steels will oxidize will vary greatly but generally care must be taken to avoid rust. Water is the primary agent of rust but foods that are very acidic of base as well as salty will have an extra reactivity during cutting. Wipe dry during heavy use and or after washing (soap is OK, avoid using the abrasive side of sponge if possible) always keep knife from soaking and out of dishwashers.
Carbon steel will form a patina with careful use, some prefer to remove it often others like to cultivate it, it’s up to you. If orange rust forms remove it with the finest abrasive possible (coarse abrasives will invite further rust by providing , we like to use the mud that forms from fine Japanese finishing stones on a rag to polish off light rust, silver polish pastes with silica will function in the same way. For deeper heavier rust, Flitz cleaner, a very fine sandpaper or scouring powder can be helpful.
Stainless steels are a variety of alloys with over 13% chromium content, stainless steels vary greatly in their stain resistance but all can rust under the right conditions. Generally higher quality cutlery stainless steels (higher carbon lower chromium) are less stainless and can corrode if soaked or put in a dishwasher. There is no such thing as a ‘dishwasher safe’ knife there are only knives that get destroyed slower in the harsh conditions inside a dishwasher.
For stainless or carbon steel knives we recommend using either end grain hardwood or length grain soft wood cutting boards, for extremely hard high carbon steels dense softwood can be a better choice. Length grain bamboo is especially harsh on edges as are many plastic boards, there is no such thing as a glass cutting board (they are a square plate that hates your knives).