The official Zombies, Run web blog states that the race missions for Abel and New Canton take place chronologically "just before the finale" of season one, though I've seen multiple sites saying the chronological order places them between Patient 29 and Virtuous Circle. And now that training missions and Zombies, Run! 5K have been released, you may want to run those before Season One.
As each Race mission in order seems to contain references to the next race mission, I would suggest running them in order (if you have the endurance or desire to run them). If you don't, you can read the transcripts on the Wiki or turn off the GPS and just listen to them, as though another runner assumed your number in your place. Canon is what we make of it, after all. Each set of race missions is meant to be run in ascending order, with the second set immediately following the first.
Supposedly, the Supply missions are interspersed throughout Season One and the Airdrop missions are peppered throughout Season Two as shown on this post. There doesn't seem to be any sort of in-app overview listing all the missions. On my app's mission page they are split by category, with Story missions being shown separately from Airdrop, Race, and Supply missions. The 'next mission' feature only cycles through the Story missions, and only if you have them downloaded. Otherwise, the app will switch to Radio mode.
