What happens to shared folders/mail when I disable/remove a mailbox in Exch2010 and which is better to get space back?

Question

We have a number of old mailboxes taking up room.  The users are long gone and I looked into removing them.  The clients of these users have been moved to others.  The users had shared folders that held this info.  I have a few questions
about the removal.
1. Is there a difference in time before space is given back if I disable versus remove the user in EMC?
2. If an ex-employee had folders that others are sharing, what happens when I do the remove/disable?  Will the folders still be out there on the people who had it shared or will it vanish from them too?
Thanks for your help.

Answer 1

"Best practice" is going to be defined by each company.  I worked for Microsoft for 13.5 years, assisting over 100 large companies deploy either Windows or Exchange, and none had the same definition for their "best practice". 
If you need access to a mailbox for a time period, you figure out a way to keep it.  If you want any terminated employee's mailbox gone tomorrow, it is gone tomorrow.
I am a fan of having some sort of process that runs periodically to clear out unnecessary mailboxes and accounts, but if there are business reasons for keeping them around, that needs to be defined into the process.  In my current company, terminated
accounts are kept for 30 days, mailbox included.  We give mailbox access to a different employee if required and tell them that if they need anything, they need to pull it into their own mailbox.  Then, when the account disappears, the mailbox goes
into the dumpster.  So, if someone forgot to pull a message, they tell their boss and live with the consequences.
But again, that's just another example of how it might be handled.  You get to define what will work for you, including pulling your business units in to help with the definition.