You can have as many different signature files as you wish, any of which can be used on a folder-by-folder basis if required by configuring the folder setup via the Folder Properties menu option.
You do not need to include a signature separator - the standard is '-- ' (dash dash space). This will automatically be placed at the top of your signature, so that a properly-configured mailer will not quote anything below it in replies.
The signature separator can be altered by going to Configuration 
Preferences Signatures, more information here.
Creating and amending signatures
To edit or add Signature Files use Configuration Edit Signatures.
Click a hotspot on the image below for further information.
