The hardness is an important number for that purpose. You also need the BLFC, although that is often 0.127 on the 7000. Those two values can cover most of the info needed. Confirm that the tank is 13" x 54".The number of people, bathrooms, etc are not important for programming that unit. Iron and manganese are important if the water is not treated city water. If it is city water, the water department or water company can give hardness. If they give a range, usually you will program for the hardest.
You want to get an Hach 5-B hardness test. That can check the actual hardness of the incoming water, and it can check the softened water to see how things are working. If you are on your own a well, you will want a lab water test. I like
http://www.karlabs.com/watertestkit/ kit 90. Figure about 2 weeks after you order to get the kit by mail, sample, mail the samples back, and receive the results by email. This gives good value for money for most situations IMO. I am not a pro. Typically county tests are much less complete, and may not even measure hardness or iron.
Remember that you don't run the water for the lawn through the softener, and yet that was going through your water meter.
This is a typical example if we assume H=18 and DLFC=0.125:
System info (not programmed)
salt lb/cuft : 6 ; A choice ( efficiency vs capacity)
BLFC : 0.125 ; Brine Refill rate GPM
cubic ft resin : 2.5 ; Same as (nominal grains/32,000)
Raw hardness : 18.0 ; including iron etc
Estimated gal/day : 260.0 ; 60 gal per person typical calc
Estimated days each regen : 9.7 ; presuming days each use reserve capacity
Fleck 7000SXT Settings:
DF = Gal ; Units
VT = dF2b ; Downflw/Upflw, Double Backwash dFFF=brine first
CT = Fd ; Meter Delayed regen trigger
C = 50.0 ; capacity in 1000 grains
H = 18.0 ; Hardness grains after compensation (unknown iron)
RS = cr ; Cr = base reserve on recent experience
CR = 0.0 ; 0 is default (leave it)
DO = 7 ; Day Override (typ 28 if no iron/Mn)
RT = 2:00 ; Regen time (default 2 AM)
B1 = 8.0 ; Backwash 1 (minutes)
Bd = 60.0 ; Brine draw minutes
B2 = 5.0 ; Backwash 2 (minutes)
RR = 10.0 ; Rapid Rinse minutes
BF = 40.0 ; Brine fill minutes
FM = t1.2 (usual) ; t1.2 is default flow meter
If H is another value, you can change just that one number.
Edit: Record the original settings before making changes. In the absence of contrary info, I would leave the existing H as it is.