Lately I got hold of some Kodak T400CN, the ancestor of BW400CN. The expiration date is 2001. Since it is developed with the C41 process, should I shoot the film at speedbox or one stop slower as it would be the case with a regular color film?
Another question about it, although it must have been discussed quite often in this forum. What would be suggested for developping the film with B&W developper (developper + time)?
I'd say extra exposure would be good.
As to developing as B&W, I wouldn't.
It is said that B&W chromogenic films such as the Kodak and Ilford versions in fact produce better negs at EI 200. There is less grain at lower speeds in chromogenic B&W films. So one stop less would make sense anyway unless you really need to use full box speed.
If you have some( as in several films) I'd be tempted to take each scene twice at EI 200 then 100. Check the negs on return from the lab and have the "better speed" negs developed. On your second and subsequent films you will then know the best speed