InfoPath Dev

What I want is to only make a from read-only once a manager has "approved" the form. So for instance, someone fills out the form (requesting travel) with their cost estimates. I want them to be able to change their estimates if they need to until the travel is approved by the manager at which point the form needs to go to read only. ...

I created a form and what I wanted was a "Sum" at the bottom based on choices made above. So for instance if they approve the formatting then the score goes up by 25... if they like content then the score goes up by 25... (100 possible). I used Yes/No for two choices and the other choice is 1 of 5 check boxes (Excellent, good, etc.). ...