Collapse Text Module and Bullets
CSS

I'm going to assume you are using the default markup that the Collapse Text module generates, which is fieldsets. I'm being intentionally verbose in the CSS rules below so you can see the html elements along with the classes I mean to target, just in case your markup is different. You will probably not need so much specificity. 

To insert bullets before each title, you can use the following CSS in your theme:

fieldset.collapse-text-fieldset legend span a.fieldset-title {
    display: list-item;
    list-style-position: inside;
}

html.js fieldset.collapse-text-fieldset legend span.fieldset-legend {
  background: none; /* Removes the arrows */ 
  padding-left: 0; /* Depends on your theme */ 
}


Outcome



Explanation

Collapse Text wraps each collapsible chunk of text in a fieldset and adds a few wrapper classes like collapse-text-fieldset. I suggest specifying one of the wrapper classes before targeting anything inside the collapsible fieldsets to avoid selecting all of the fieldsets on the page or on the site depending on where in the theme you're adding the CSS. 

Your theme may have different indentation or padding applied to fieldset elements. In my test case there was 15px of padding-left on all fieldset legends as part of the base styles of my theme, and I wanted to remove that in order to avoid unnecessary space.