With regard to the dates, are you requiring that we calculate returns over 1 year defined as the time between FTDOY and LTDOY, and NOT the full 365 (or 366 for leap year) calendar year? 

First, there are about 252 trading days in a calendar year for equities. We generally obtain this return and report it as an annual return. These dates are the ones that WRDS/CRSP provides without modification.