Difference Between Matching Columns, Average Formula Inc. Text & Highlighting Number Value

Hello All,

Today I am trying to get a few things sorted out. And I know many of you are really knowledgeable and love helping... SO;

The first issue is:
I need help with a formula that is on Sheet!ThisMonth, in columns D2:D4 to look at last months columns Sheet!LastMonth D2:D4 LOOKING AT THE EMPLOYEE NUMBER ONLY, not the names. To then look at both the Sheet!ThisMonth and Sheet!LastMonth C2:C4 values and have the difference.

Secondly:
I also need to get the Average percentage in E1 to be similar to AVG: 52.9% but whenever I try
="AVG: "&AVERAGE(C2:C4) it comes up as: "AVG: 0.529"
It is shifting the decimal over and dropping of the percentage. Now I can just add a &"%" on the end but this doesn't solve my decimal problem, It's still "AVG: 0.529%"

And Lastly:
If there's blanks in any of the cells in B2:D2 I would like for B1 to be highlighted red. If all cells have a number value in them, I would like for it to be highlighted green


I know it's a lot I apologize, but anything you guys can help out with would be GREATLY appreciated! Thank you in advance!