Regarding 2
For an example of a subroutines that send an email, look in the Administrator Guide in the Workflow Examples chapter for the topic "Example: Sending Email". This provides examples for Tests and Defects, but you can extrapolate from these for Requirements. You may need to refer to the Database Reference for information about the REQ fields, if you want to customize what information is in your email.
Regarding 3
Please describe in more detail what you need to accomplish. There does not appear to be any default status dependencies coded into the Defect module in my ALM v11.0 environment.
Regarding 4
Technically a Library and a Baseline can be created at any time for supported entities regardless of their status. Are you trying to prevent creation of a Baseline if the status is not Approved?