Issues resolved.

I reached out to ServiceNow Support (support.servicenow.com) and they helped me resolve the issues.

1. For the Order Guide Choose Options, I navigated through Service Portal > Widget Instances and opened the SC Order Guide widget (Package: Service Portal - Service Catalog (do not activate - see plugin description)).  In the Widget tab, selected "SC Order Guide" in the Widget field.  It was set to "SC Order Guide Deprecated".

2. For the inability to uncheck the "Show Include Toggles" checkbox in the Order Guide record, I had the checkbox on it twice.  In Configure > Form Layout, I removed the checkbox from the top section and kept the checkbox in the Service Portal section at the bottom (which is visible by default).  After doing this, I was able to do it.

Just wanted to share in case this is helpful to someone else.

Thanks.