JKM@SA:How do we get it to show only Active Items?
Great question!  I just finished some customization on my end and had to do something very similar.  
Create a copy of the QuickBooks_Estimate screen and open up the screen designer to edit this page.  Once you have your copy open click edit on the grid for EstimateLine.  On step 2 of editing click the Advanced link for the Item field.  On this page you'll see a Filters section and you should be able to build a filter to only show Active items.
~C