SysAid Product Manager
Re your first question, currently, the option to set your email account as a default email from within the service request is not supported.
I will add this as a Feature Request.
You can create your own signature that will appear in your all messages.
In order to do this, go to Preferences -- > My Settings.
For additional information, please refer to the following help page: http://www.sysaid.com/help-page.htm?helpPageId=4162&helpPageName=Preferences.htm