Try this- Dates will be in cells A1, A2, A3, & A4
Put this formula in Cell A5: =COUNTBLANK(A1:A4)
Put this formula in Cell A6: =IF(A5=0,"All Complete", "Need More")
Or, they can be combined into one cell =IF(COUNTBLANK(A1:A4)=0,"All Complete", "Need More")
Alternatively, you can use COUNTA to test for the number of cells that are filled in and change the zero to the number of cells monitored and then reverse the message alternatives.
If you use conditional formatting for Cell A6 you can also change the color of the text to make the status more noticeable.
I'm not sure I understand the second question, but I think the Count functions can be applied there somehow.