You've got a lot of questions here.
First, can you show us the place you see the red exclamative point (exclamation? !)? In my image below, you see the red exclamation next to name, that just means it is a required field. It sounds like this is the actual certificate question. You can create conditions (restrict access in the images below) in the activity settings when the certificate becomes available (Scorm 1=passed OR Scorm 2=passed OR Scorm 3 = passed). My image show must complete all, you can change that to any.
First, can you show us the place you see the red exclamative point (exclamation? !)? In my image below, you see the red exclamation next to name, that just means it is a required field. It sounds like this is the actual certificate question. You can create conditions (restrict access in the images below) in the activity settings when the certificate becomes available (Scorm 1=passed OR Scorm 2=passed OR Scorm 3 = passed). My image show must complete all, you can change that to any.
Certificate is a little tricky--first you set up the activity (activity settings). Then you actually create the certificate. Once the activity is created, you go to the editing widget and choose Edit certificate. (I think you are there already) Then you build all the items in. The red exclamation won't disappear. At the bottom, you have add elements and a drop down next to it. You choose which elements you want, which can include grade. All the items in my example were added by me. You may need to do something fancy (not really, just something different than standard) in the gradebook to get the single required score to work and use the course grade, not a module grade.
If some of your question is related to how the course completion shows in the dashboard, that is different.