I'm sorry hear you had some crashes. Unfortunately, you are not the only user that has reported instability. I am devoting essentially my whole day to improving that side, so I think you should notice improvements quickly, since I push bugfixes on a daily basis (sometimes even more often). By the way, the latest version is 1.0.18. Are you running that version? I ask because there was a bug where you couldn't change the name of a record loop, and couldn't choose which record loop you wanted a play loop to refer to. It also caused crashes. However, I'm almost certain I fixed it in v1.0.18. If you weren't using that version, it could explain why you had the problem. If there still is an issue, I'd appreciate you telling me if you get the chance, because it's not happening on my machine.
I should mention here that the app auto updates, which means that while you use the app it checks in the background for new versions. If you exit and then re-run the ALK, it installs the new version. You can check in the "About zenAud.io ALK" menu that the version has increased. What I really need to do is to make it so that when the version updates, you're given a kind of "welcome screen" that shows you you've updated, and also tells you what the changes are (e.g. bug fixes, enhancements, etc.). That way you know you're using the "latest and greatest". Again, I think this will be a big issue for the first two weeks, after which I expect to get 90% of the problems. The remaining 10% will most likely be harder to identify (only appear on certain hardware, plugins, etc.) and take much longer -- but that's ok because for the great majority of users/use-cases the application will be basically stable.
To answer your question quickly:
Green pencil: either playback (MIDI or audio) or drawn (i.e. curves for control or menu for command) automation. Green means "something that I will not perform live -- either I will use something that I just recorded or I will draw something"
Red pencil: stuff I will record live (MIDI or audio) or automation I will perform with an encoder in a live setting. For the latter, you of course need to "learn" the encoder source.
One little complication: since record loops (drawn with red pencil) are the actual repositories for notes and audio data (whereas play loops simply refer to a record loop), imported loops (audio or MIDI) appear as record loops (this is a bit unintuitive and may change in future versions). To prevent overwriting them when you hit record, they are automatically set to be locked which prevents them being written to. Any record loop can be locked, and also any track (which locks everything inside). You can lock a region or track from its menu (right-click or click on the hamburger icon) or by hovering over the loop or track and pressing 's' (for seal = lock).
Thanks for using ALK and for your patience. Have a good evening!