> -gltLabel 1 'ageearly.rew-pun' -gltCode 9 'Ant : 1*rew -1*pun age : 0' \
> -gltLabel 2 'agemid.rew-pun' -gltCode 9 'Ant : 1*rew -1*pun age : 1' \
> -gltLabel 3 'agemid.rew-pun' -gltCode 9 'Ant : 1*rew -1*pun age : 2' \

Yes, these three lines assess the difference between 'rew' and 'pun' when age is adjusted at 0, 1, and 2, respectively.

> If I center my variables ahead of time, do I still need to use qvars and center again (or if not "needed" is it recommended)?

Yes for both. For centering, set it to '-qVarCenters 0'.

> -glfLabel 1 'val_age' -glfCode 1 ' Task : 1*rew & 1*pun age_c :' \
> -glfLabel 2 'val_age2' -glfCode 2 'Task : 1*rew & 1*pun age2_c :' \
> -glfLabel 3 'rew_age' -glfCode 1 ' Task : 1*rew age_c :' \
> -glfLabel 4 'pun_age2' -glfCode 2 'Task : 1*pun age2_c :' \

I never did something like the first two lines. So I'm not so sure if the program would behave properly.

The last two line should be the following?

-glfLabel 3 'rew_age' -glfCode 3 ' Task : 1*rew age_c :' \
-glfLabel 4 'pun_age2' -glfCode 4 'Task : 1*pun age2_c :' \

which might be better done through -gltCode.

Gang