This is a good writeup. My company uses Slack for communication, and we love it since it's browser-based and therefore platform-agnostic. We also had a group write a custom integration that assists people in carpooling to lunch.

I do have some conversational criticisms:
Comments in source code doesn't work as well as one might hope; nobody wants to try to keep comments up-to-date after the fact. I believe code should be self-documenting: do a solid job of naming classes, methods, and variables, and you'll be better off.

I also have to disagree with, "put low-level requirements in ticketing systems." In my experience, adding extra unnecessary steps to software development will only bog teams down (and they probably won't follow through with it consistently, anyway). My teams deal with product managers which write the tickets/cards/stories for us (they give us work to do, and we do it) and so it wouldn't make any sense for them to write anything more detailed than the high-level requirements.