Disable select fields in a drupal webform
When you are on the page for editing the form component, you can change the widget from select options to a textfield. Then the option to disable becomes available.

However, it will display the value of the select, not the label - for example I tried with Name Prefix and for "Dr" it put "4". 

But if you are dealing with custom fields where you can set the values to be the same as the labels that shouldn't be a problem. 

Where it might cause a problem is activity status - could you get away without showing that?