Welcome!

technology has likely advanced in the 11 years since you last investigated this issue, one can assume. I am not aware of any limitations on lights when rendering in iray, but perhaps there would be limitations if using legacy renderers and features such as 3delight, which some people are wont to do....

As of writing this, only official Daz3d.com vendors can make hair in other software and convert to SBH. Nevertheless, we are able to create SBH within Daz Studio itself using the SBH Editor. See tutorial below: https://www.deviantart.com/uncannyvalet/journal/Creating-Strand-Based-Hair-Daz-Studio-957...