Ladder and post-ladder discussion

Hi all,
I am new to D2R ladder and would like to know how it works. I would like to create a discussion in which the most amount of information is shared in order to have full knowledge.

Also, once the ladder period is over, (6 months, right?) what happens to the shared stash and how does it become non-ladder? Will I have to create Mules?

Thanks!

After the end of the season, laddered characters become non-laddered, and therefore it is possible to transfer items via shared tabs.