#VALUE! Question and Sum Average Question

Gosh, not sure I can articulate this request clearly without confusing the reader (apologies). All the data has been sensitively edited and all my questions refer to the 'Reports&Charts' Tab

Firstly I would like to be able to 'average' the process times for each month and populate the revelant cells as per the other calculations ie early, on time and late.
Secondly, for those units which haven't been processed I currently recieve a #VALUE! in the cell (particularly in the two lower charts). Ideally I do not want these not to be included in the count for early, late and on-time result but to be shown seperately in another cell called 'still to process'
is this possible