Enable Workspace mode in FMG

hi,

we would like to use the lock feature when an admin is making change/FW policy push.

my questions are:

1. is it "safe" (no downtime/outgea) when enabling "workspace" in FMG? just want to "lock" or create workspace for a specific ADOM only.

2. what mode do i choose and what's the best practice?

3. do i just choose "workspace" then apply?

4. what is per-policy lock?

5.does a user always need to "lock" the ADOM and create a new "workflow session" when making a change?