Regarding humidity reading on 12 bits:
humidity = -4.0 + 0.0405 * val + -0.0000028 * val * val;
note the value C1 on the table 7 is -4.0 C2 is 0.0405 and C3 is -0.0000028 or (-2.8000E-6) as stated on table 7. ORH is the output from the sensor.
on temperature we have:
temperature = (float)val * 0.01 - 40;
from Numeral 4.3 T = d1+d2* SOt
for 5V d1 is -40 and d2 is 0.01 again for 14 bit conversion SOt is the 14 bit value read. You are right compensation is not done there but it shouldn't be problem as it might be done using the formula on numeral 4.2
Hope this is what you are asking for, let me know.