-It's a medium-sized military vessel, probably analogous to something like the Bob Hope Class cargo ships, so while not the biggest ship in the fleet it's still pretty big and in precarious shape, making a thorough top-to-bottom search by one or two individuals impossible in the narrow timeframe they have.
-It's fairly standard in layout. There's three decks - top level consists of the captain's quarters and the bridge. Second level is the cabins, recreational area and mess hall, and the third lower deck contains the engine room and cargo bay. The machinery is what you'd see throughout Aifaran albeit a bit more advanced because this is (was) a top-of-the-line Sentry vessel. What they would see is a mixture of magic, biology and tech (notably the work of the Muin and Kedanese engineers), but the keen eye may recognize Chihuelan tech mixed in. Like the rest of the Narrakra, it would be in a sorry state of disrepair.
-The fungus, insect carapaces, and rust can be taken as samples. There's also that carcass on the lower deck. Depending on where Kit and Rutile explore, there may be other samples that the crew have gathered.

There is no specific direction your characters need to go beyond what intrigues you. They'll only have time to explore one - two areas thoroughly before the Sentry wises up and gives everyone onboard the boot however.