Date formula and count.

Hello,
I have a running excel sheet that I need to give a monthly report of my accomplishment.
1. I have this formular in Meet goal column =IF(C2>B2+2,"N","Y"), but I need help revising this formula so that it will not look at weekend and holidays, and leave blank if N/A is in notice sent.
2. I need to get the percentage of accomplishment every month. I have to mannually count number of "Y" devide by the total of "Y" and "N". How can I have I set up the pecentage fomula for this?
3. How do I set conditional format so that if Notice sent after 2 working days from the DT assigned, this cell will highlighted?

Your kind help is appreciated!

Best regards,
KAT