there is no limit for posting but there is an interval for every post, if i'm correct every post there is an interval of 6 minutes and here's how it works first you need 14 days to update your rank to jr. member, then in that 14 days you need to have 30 activities every 14 days they will update your rank it depends how many activities you have.
And for this to become Jr. Member you need to have 30 activities
Member: 60 activity
Full Member: 120 activity
Sr. Member: 240 activity
Hero: 480 activity
Legendary: I thing above 700 and up.
Hope you get some ideas here...