How to display multiple categories of webapp items in list view? Changing listbox list to checkbox list to select category in submission process?

Question

Hello!
1.
I am trying to get my page to list webapp items that are part of a few categories. I understand that if i want to view only one category, I just need to do the normal process of choosing that category and placing it out. So my question is: How do I display multiple categories of items in a webapp in a single page. I've tried this
{module_webapps,WEBAPP_ID,c,CATEGORY_ID1,,,,10,,1} {module_webapps,WEBAPP_ID,c,CATEGORY_ID2,,,,10,,1}
This only displays the everything from the first category, then everything from the next, which will not make it in order of date.
I've also tried this for fun:
{module_webapps,WEBAPP_ID,c,CATEGORY_ID1&CATEGORY_ID2,,,,10,,1}
How can I go about doing it?
2.
I am looking to allow users to input a webapp item and allow them to select a category to tie to that item.
<label for="CAT_Category">Category (You may select more than 1)<span class="req">*</span></label>
    <select name="CAT_Category" id="CAT_Category" class="cat_listbox" rows="4" multiple="multiple" style="height: 60px;">
    <option value="CATEGORY_ID1">--- Option 1</option>
    <option value="CATEGORY_ID2">--- Option 2</option>
    </select>
Is it possible for me to change the listbox style into a checkbox style such that the user doesn't have to control+click multiple options?

Answer 1

No answer to No.1 but I really want to find it out too.
No.2 
If you already know list of the categories & ID you can manually create a list of checkboxes
<input type="checkbox" name="CAT_Category" value="89081" />
<input type="checkbox" name="CAT_Category" value="89082" />
<input type="checkbox" name="CAT_Category" value="89083" />
something like that should work