The complexity argument has problems because in the small error bars of dna replication, it's so easy to introduce a sequence that actively hurts the animal, or is useless. Producing a whole new limb or whatever is way more complicated that we'd like it to be.
The discussion overall is part of a larger move by the intellectual/theological groups to bring back language (and psychology elsewhere) back into the old energy and matter world-view.
I agree it's hard to answer, the James Tour video is a nice place to start because he talks about biological engineering problems that his students are covering for him. They make little nano-robots and the like in part of the presentation. It seems inevitable that we won't see an overall answer for thousands of years.