thanks for the tips about CarPlay development. I'll definitely target parity with the web app at first so hopefully it'll be something I can get access to eventually

regarding (1), yes, you keep the routes you made even after your subscription ends. the limits revert to the free tier so if it had more waypoints or was longer than that then you just can't add or move waypoints. removing waypoints to get back down below the limit works and you still export your trip to formats included in your tier (e.g. google/apple/waze)

you could absolutely pay for a month just to plan and export all your trips for the year, bookmarking them with google maps or saving the files for your GPS for instance -- not a problem. I am currently exploring alternatives to monthly & annual subscription schedules to further support seasonal usage, too

per your 2nd question, that's correct, only the creator needs to pay to have 2+ collaborators. you can try it out on the free tier with 1 person at first to see if it works for you. if you just want to share maps publicly you can do that without subscribing, too