Date Field not working correctly

I set up a form with multiple date fields. I formatted all of them as mm/dd/yyyy format.
 
When I went to test the fields, some of them allow me to enter 8 number, for example 12132011 and it formats it to 12/13/2011
 
In other instances, if I enter the string of numbers without the '/', it rejects the entry and says it must be entered as mm/dd/yyyy.
 
All fields have been entered identically.
I started out with a Word Doc form and uploaded to Adobe and have been going into properties to format fields. All of my other fields work fine - including phone number. I'm able to enter 10 digits 1234567890 and it formats it as (123) 456-7890
 
Where am I going wrong with the mm/dd/yyyy field?
 
Also - as an aside, is there any javascript anywhere that can add a calendar drop-down to the date field?
 
Thanks!!!