Using custom validators, you can easily manage these system attributes. To do this:
1) Log into your admin dashboard and navigate to Manage > Service Types > Custom Validators
2) You will notice that some validators may already exist. You can edit these validators or delete them as you see fit, using the links on the right.
3) If none of the fields that you want to manage are present in this list already, you can add a new validator by selecting 'Add Validator' in the top right. This will take you to the form where you can manage these attributes
4) At the top left is a dropdown where you can select the attribute that you want to update. Let's say for instance that you wanted to make listing type mandatory. You would start by selecting 'Listing Type' (as we have in the screenshot above) and then ticking the box labeled 'Required'.
Note that you also have the option of specifying the 'Valid Values', which really just means that if this attribute is a dropdown element, your valid values are the options that appear in that dropdown. So for the listing type attribute, these would be the actual types that users are selecting when creating a new listing.
You also can specify the min/max character limit, for input or textarea attributes.
5) Don't forget to click 'save' when you are finished customizing your system attributes.