The Management account is what the JSS uses when it needs to run policies and escalate privileges to root level to do things like installs. Its basically a requirement to do just about any management on your Macs.
While you can technically just use your existing local administrator account for this instead of creating a new one, its often cited as best practice to create a Casper Suite only management account, and leave your local admin account for other purposes.
As for the options you mention, Hiding it just means it creates the account with a sub 501 UID and makes sure it doesn't show up in the Users & Groups preference pane. Edit: It also places the account in /private/var instead of the standard /Users/ path.
Allow SSH for management account only is a security piece that would prevent any other account on the Mac to be used remotely for remote login (SSH) purposes. The Casper Suite benefits from having SSH access to your Macs using that account. Its used for a variety of different tasks. You can choose to leave that unchecked and then other accounts on the Mac can be added to the remote login list and thus SSH to those Macs.
Hopefully that helps clear things up a little.