We should also indicate times. In terms of orbits, we are certainly going to need to know what a lunar month is, what a solar year is, what a phase month is (the orbit of the second moon), and probably what the orbit of the second star is (you said something like 500 years but it'd be nice to know). The orbits of the other planets can be whatever they come out as (unless someone has some specific plot ideas to use for them which require they be a certain way).

We might also consider what a common week is. The 7 day week on Earth is religious in origin and possibly lunar, though obviously that doesn't work out exactly. Our world could have 8 day weeks, 9 day weeks or whatever. I think however shorter than 7 days is too short of a week and 10 or longer is too long (why the French choose 10 days for their revolution is beyond me, why not 8 if you want easy calculations?). Obviously this would not represent all cultures but we should have a generally understood week that we default to when not otherwise specified.

Also how long a day is would be important to know to I'd guess, though any amount of time could be divided into 24 easily enough.