if you create the checkbox on a new line, it will automatically be shifted to the left.
to add the bulleted list, use:
<ul>
<li>I accept the User agreement and privacy policy (note that this is a link to the file)</li>
<li>I am at least 18 years old.</li>
<li>I may receive communications from XYZ related to my membership.</li>
</ul>
Yes, the custom code will be wiped out if you edit the Form contents.