Logical Test For Date Ranges?

I have a spreadsheet where I have a list of patients who were evaluated on a certain date unique to that patient. Some of the patients have a subsequent date of death, and some do not (they're still alive).

I need to create a logical test which indicates whether or not the patient died at specific intervals after their unique evaluation date-- at 3 months, 6 months, and 12 months. Additionally, I need to measure whether the patient died at 0-6 months, or 0-12 months, or is still alive.

In other words, if Patient A was evaluated on 1/1/2008 and subsequently died on 10/31/2008, I need to do a logical test that says 3 months = false (no death), 6 months = false (no death) and 12 months = true (death). True = 1 and False = 0 (so I can do a simple column add to figure out how many died at each interval). Additionally, for the 0-6 month test it should calculate = 0, but for the 0 - 12 month test it should calculate = 1.

I'm totally stumped as to how to do this. Currently my spreadsheet reads as follows: (I've put ** next to cells that I need formulas to calculate. If no **, assume it's a value I've inputted manually)

A1 = Patient number (numerical order)
B1 = Patient Initials
C1 = Initial Evaluation date
D1 = Date of death (if any- blank if patient is still alive)
E1 = Patient death indicator (1 = dead, 0 = alive)
F1** = Indicate whether or not patient died within 3 months of evaluation (1 = dead, 0 = alive)
G1** = Actual date of death within 3 month interval
H1** = Indicate whether or not patient died within 6 months of evaluation (1 = dead, 0 = alive)
I1** = Actual date of death within 6 month interval
J1** = Indicate whether or not patient died within 12 months of evaluation(1 = dead, 0 = alive)
K1** = Actual date of death within 12 month interval
L1** = Did patient die within 0-6 months of evaluation? (1 = dead, 0 = alive)
M1** = Actual date of death within 0-6 months
N1** = Did patient die within 0-12 months of evaluation? (1 = dead, 0 = alive)
O1** = Actual date of death within 0-12 months