In all seriousness, with respect to the Galena's position at Glendale and Malvern Hill, it's visited primarily because it is the flagship; McClellan goes to consult with Rodgers, and Rodgers' flagship is the Galena.
It was in optical telegraph (semaphore) contact with Malvern Hill. We have records of many messages sent back and forth, so this seems pretty clear and unambiguous. The messages seem to have taken only a few minutes to transmit in any given case, because we have at least eleven messages sent during the time McClellan is on the Galena and he's not on board for all that long.
There is a mistranslation with regards to what the Comte du Paris said, it is a type of conjugation exclusive to French.
"Lorsqu'on à mène pendant quelques jours une vie aussi rude, l'on se sent tout dépaysé en arrivant sur un navire ou tout est propre, ou les officers ont ligne blanc et ou l'on trouve subitement un bon dîner et du bon vin."
What he says is odd is being on a ship where "you can get" a good meal with good wine, rather than saying that there actually was one that they partook from.
It is possible that McClellan actually did eat on the Galena, but to my understanding the Comte du Paris does not say that he does.
As a warship the Galena seems to have been fairly capable; she's more vulnerable than other ironclads but less vulnerable than unarmoured sloops. She duelled Drewry's Bluff and took 44 hits, of which 13 penetrated the armour, but I rather suspect that those hits would have been more damaging if she didn't have the armour, so what I wonder is if she fell victim to the "all or nothing" fallacy where armour that does not completely protect is seen as of no value.