Planetary Information

=== The general length of the year ===
The general length of the year is 420 days long. Like everything, this figure is not exact, being short by an amount that for more perfect precision requires a leap day being subtracted once every 13 years.
The factors of 420 are: 1, 2, 3, 4, 5, 6, 7, 10, 12, 14, 15, 20, 21, 28, 30, 35, 42, 60, 70, 84, 105, 140, 210, 420
Meaning that religious festivals can happen along any of these periods and will fit evenly into the year.
=== Traditional seasons ===
In tropical areas, the length of the year is taken as 400 days, with a inter-year holiday period to make adjustments. This leads to 400 "degrees" in a circle, and 100 "degrees" in a right angle. 
This can be found in many calculators where the option is there to measure angles in "gradians" (see wikipedia: http://en.wikipedia.org/wiki/Gradian
The year typically starts with the first day of spring, although some cultures will choose other dates, such as the date of the founding of a city, a nation, etc.
Seasons are scientifically 105 days long, although traditionally it is 100 days of spring, etc with a 5 day festival between seasons. This may or may not coordinate with the inter-year festival, depending on local culture
=== The Three Moons ===
There are three moons, all of which contribute to various calendar cycles, but only the largest contributes to meaningful tides. They all show visible disks, and go through visible phases.
Their periods are rough multiples of each other, which helps contribute to the stability of the lunar system. The slowing go in and out of synch with each out, and this is said to have astrological import. Several calendars have several different month systems at the same time, reflecting the interaction of the several moons.
The closest and largest moon has a period of approximately of 31 days. There would be roughly 13.5 months in a year 
The middle moon in size and distance has a period of 63 days 
The farthest and smallest moon has a period of 124 days