The setting in interesting and very unusual. What did you envision a typical adventure to be? Is it more of an endless travelogue or a journey of correcting or repair 'flaws' of the locations journeyed to? Also would to PCs be very powerful compared to the average persons they meet or is this the common level of power in general?
You can use it as a tool box, using just the classes in regular settings, or use the key system as an alternative to space travel, mixing the adventure tables and foes.
You could just be delivery services, mercenaries, adventurers, explorers...jumping from issue to issue.
Class wise, the options here are comparable to the original Troika game, and since Troika can be very bonkers, suit yourself regarding power level.