I can code on ketamine as long as I'm not doing anything novel nor dealing with something that requires a global, holistic view of a system and its interactions. Once you've done something for long enough it becomes subconscious, so as long as I'm still able to type code in and see what I've typed (to correct all the mistakes lol) it's possible to program while under the influence.

Maybe? I usually don't (not parent) but it definitely gets me around brick walls sometimes if I'm having trouble thinking outside of the box and a different strategy is needed. It can make boring problems seem more interesting too. Overall, I wouldn't say it's harmful, but it's not like it's enhancing much either. Ymmv.