Yes, photosynthetic slugs have been known for years (decades). What was unknown was whether any of the genes required for photosynthesis have been incorporated into the genome of the animal as opposed to solely using the genetic material in the consumed chloroplasts. (Yes, chloroplasts do have their own genome.) It was just now shown and reported that the genes to make chlorophyll have in fact been stably incorporated into the slug's genome. That is news.

No, the statement is essentially correct. The slugs harvest (i.e. gain) energy via trapping photons with chlorophyll. They store that energy as chemical bonds in sugar molecules. They then release the energy as needed by metabolizing the sugar. Photosynthesis is the coupled capturing and storing of energy so saying that it "gains" energy via photosynthesis is a reasonable simplification.

First the "six possible changes" is only referring to single nucleotide polymorphisms (SNPs), which is the substitution of on one base for another. There are more complex alteration, insertions, deletions, inversions, etc. are not counted among these six. For a SNP to become "fixed", that is stably maintained through subsequent replication cycles you have the initial mutation event (altering a base) but then you must also have the complementary substitution on the other strand of the double helix. If an A is changed to a T on one strand then the complementary T must subsequently be changed to an A to maintain complementarity of the double helix. Once the mutation is fixed it is impossible to tell if the original mutation was the A->T, with complemnting T->A, or vice-versa. More properly these mutations are written as change in the paired bases AT->TA. An AT->TA is indistinguishable from TA->AT. The six possible changes are:

AT->GC
GC->AT
AT->CG
AT->TA
GC->TA
GC->CG

Bzzzzzt, wrong. Sorry, thanks for playing. Apple Remote Desktop is $499.00 for an UNLIMITED number of managed clients. You license the management computers, not the clients. You would buy one copy of ARD Unlimited for each administrator's workstation.

Mr. Orwell, is that you?

It looks like that Wikipedia page may need to be updated. From TFA:

"The analysis showed it is highly unlikely that much interbreeding occurred as there was "very little, if any" Neanderthal contribution to the human gene pool, said lead researcher Svante Paabo of the Max Planck Institute."