Must find duplicate names between two sheets, transfer some data between the dupes then...

Two Sheets--One Big Mess.

A tiny bit of background might save a lot of explanation. A co-worker and I were assigned a workbook filled with data and told a certain start date on a project--my co-worker started before the date and has entered tons of information into their copy of the work book. I have now worked on the book also (so we have 2 copies with different information). We would like to merge our copies into one master sheet--removing all duplicate names, being sure not to overwrite sheet 1's info with sheet 2's, but having sheet 2's work fill in any blank fields on number 1. Any help would be greatly appreciated.

1) Need to merge FirmName2 into FirmName1 with some rules
a) FirmName2's information in Cell F needs to overwrite blank information in Cell F in FirmName1
b) duplicate names need not be merged--simply the information in Cell F updated

I'm really new to Excel, could you help me out with using the vlookup for this problem?