Hi, Kevin.
You should really consider Michael's suggestion, the book is very thorough :)
Regarding your issue: not sure what do you mean exactly by "My SP needs a reply like this" part, as I see two potential issues in it: type of nameid and attribute's names.
If you need a custom nameid created, it's recommended to follow **manual** way of defining it described in [this doc](https://gluu.org/docs/ce/3.1.4/admin-guide/saml/#manual-configuration) (you shouldn't use the web UI approach, as it may have issues in version 3.1.4).
When it comes to attribute names in assertions, it gets more tricky. I would try to add a new custom attribute as described [here](https://gluu.org/docs/ce/3.1.4/admin-guide/attribute/#opendj) just for the sake of storing a copy of username value, and use that `http://schemas.microsoft.com/ws/2008/06/identity/claims/windowsaccountname` string as "SAML2 URI" property when you'll be registering your new attribute in web UI. You also could opt to change this property for existing default "Username" attribute, but this will have global effect on all SPs which may use it.
It's either one of these ways, or manual editing of tempates used to generate config files, which isn't covered by Community support, unfortunately.