COUNTIF? (Count number of date values in a column more than 30 days old)

Hello,

I'm working with a spreadsheet which tracks the status of various projects over a date range. New projects come in and are automatically assigned daily. I want to set several cells within the spreadsheet to tell me:

1. How many total tasks there are. I already have this part working, with:

PHP Code: 

=COUNT($F:$F) 


2. How many tasks are overdue. I've tried:

PHP Code: 

=COUNTIF($F:$F,TODAY()-$F2>=30) 


Strangely, this doesn't do anything.

3. How many tasks are new since the prior workday. I have tried:

PHP Code: 

=COUNTIF($F:$F,IF(WEEKDAY(TODAY())=2,TODAY()-$F1<=3,TODAY()-$F1<=1)) 


Modeled this after conditional formatting I'm using on the same column, and this also does not work.

Thanks.