What you describe would certainly require some additional customization of the actual WordPress setup as there is no specific function contained within the theme that would allow this.
Here are a couple of WordPress articles which may help when looking at how this can be achieved:
http://codex.wordpress.org/Create_A_Network
http://codex.wordpress.org/Migrating..._3.0_Multisite
We do have customers who have set up our themes on a Multisite network, but I cannot recall any specific examples of someone doing exactly what you describe, but technically it could be possible, it would be more than a standard installation though.
Yes, JobRoller has Indeed integration built into it, so you can dynamically display jobs from Indeed on your site. You can view the
JobRoller admin dashboard here.
Thanks.