Photoshop Elements :: Photo Editing - Auto Contrast And Unsharp Mask

I'm using PE10, and usually start with the "Quick Edit" tab to do a "Smart Fix" where I can select a desirable fix.  Sometimes I additionally do Shadow adjustments and/or Highlight adjustments, but not much else. Then go to "Full" edits.
 
- "Enhance - Auto Contrast" does tonal corrections as I understand.  However I usually see no difference after doing this.  Is that because when I did the Smart Fix, it is essentially doing the Auto Contrast as one of its adjustments?  If so, is it just a waste of time for me to do the Auto Contrast if I have previously done a Smart Fix?
 
- As the last step, I usually use "Enhance - Unsharp Mask" on my photos with Amount = 70, Radius = 2.0, and Threshold = 0.  Are those reasonable numbers?  I understand that beginners tend to over-sharpen their photos.  I've played around with various values, and these numbers seem to have worked for me, but would just like other opinions since I don't have that professional eye as to what is a great photo.  I make sure that I zoom in to print size or more when looking at the results of sharpening.