lateral gene transfer from alga to sea slug

Did you know that when sea slugs acquire the photosynthetic capability of algae they eat, they're only keeping the chloroplasts? And apparently it's puzzling that this works, because they shouldn't be able to operate without algal nuclear proteins.

http://www.pnas.org/content/105/46/17867

Two possible explanations for the persistence of photosynthesis in the sea slug are (i) the ability of V. litorea plastids to retain genetic autonomy and/or (ii) more likely, the mollusc provides the essential plastid proteins. Under the latter scenario, genes supporting photosynthesis have been acquired by the animal via horizontal gene transfer and the encoded proteins are retargeted to the plastid. We sequenced the plastid genome and confirmed that it lacks the full complement of genes required for photosynthesis. In support of the second scenario, we demonstrated that a nuclear gene of oxygenic photosynthesis, psbO, is expressed in the sea slug and has integrated into the germline.

1) I wonder how much it would take for the sea slug to make its own chloroplasts too. Maybe a lot of basic dependencies get pulled in, I suppose.

2) How heavyweight is the genetic package that lets the sea slug do what it does? Can I have a copy?