How much room was there in the boat? Enough for Buppido, Shuushar, Gal and Stena plus maybe Eldeth's body?

The boats can hold 6 plus some gear, so yeah, you'd have room for the party members and party member remains. Spare room for a KT if you wanted one too.

Stena hasn't had the opportunity to try, at least to her knowledge. 

I kind of lost track of provisions, and who was carrying what, but the KT would have had some in their boat, so you've probably got at least a day or three of food for the four of you. Not dire, but foraging will need to happen, and depending on if Slobludop is still a place to be able to expect to be able to do a bit of trade and restock, you may be fine. Though if your intent is to try to enter Slobludop peacefully, wandering in with one of their filleted citizens might put negotiations on tilt.

Galingal takes a long slow death at the sight of the dead being blood eagled on the sand.

”Do kuo-toa do such things?” he asks not expecting an answer.

Spent of all his energy he has little to offer the wounded. He will try Spare the Dying on each, not expecting it to help Eldeth but it will stabilize the derro at least.

“Leave dead kuo-toa here.“ he says while holding the boat steady for Stena to put Eldeth in.

Once in, he’ll push off and start on their way again.

After Thom notices the movement of the two silhouetted figures and the possible boat, he would immediately tell everyone in the boat that he is in what he sees. He wouldn't be quiet about it, or loud... just normal speak. He is more relaxed now with the calm water and glowing fungi and isn't thinking ambush anymore.

He thinks it's likely more KT that he notices.

So he'd tell everyone what he sees and then say "More of your friends, Ploopp? Over there, look." and he points to what he sees. 

Shuushar doesn't react to Galingal's touch, and the KT and Eldeth are beyond his care, but as he places a hand on Buppido and channels magical energy, the derro gives a start, his eyes opening wide and wild as he thrashes around, scooting backwards and looking around.

Realizing that he recognizes you, he calms slightly, but babbles rapidly in Undercommon before remembering you can't understand him, then switching to his corrupted Dwarvish.

"Howdja find us? Wherahza others? Oh, fork..."

His glance lands on Eldeth and he backs away, looking around at the dark.

"Time fer that later, we gotta go."

Ploopp and the others peer in the direction you're pointing, and Ploopp gestures and one of the KTs hands his paddle off to Jimjar and dives into the water. You can see it dashing ahead, popping its head up every so often as the boats begin navigating a circuitous route between the low islands and sandbars towards where you spotted the figures.

Thom watches with a bit of amusement as the KT dives into the water and begins to swim toward the figures. "Would you look at that!?"

As his and the other boats also start heading towards the figures, Thom would follow Lia's suit and arm his longbow, pointing it at the figures and having it ready to shoot the minute that KT indicates that the figures might be hostile/ambush etc. 

He nods at Lia and says "I wonder what or who that is, yeah?"

To the question about what KT's do Stena gestures at the bloody mess on the beach.

"Some clearly do."

Stena looks impassively at the babbling derro and gestures with her head towards the boat as she carries Eldeth and gently places her in the boat before climbing in herself. She gather's Eldeth's shield and hammer and secures both to her person. At that point she'll say to the derro,

"Buppido, did you hear the kuo-tao say anything on where they were heading? Otherwise, Sloopidoop is still the destination."

She isn't asking Galigal but she also isn't expecting any disagreement.

The KT scout returns and grabs the side of the boat to report to Ploopp.

"Grillooopodoopb says that it's a angry looking bunch, derro, dwarf and elf. Maybe we should leave them be and go around?"

Buppido will hurry to the boat and help hold it still as Stena lays Eldeth in one end and places her family gear with her.

He responds to her questioning in dwarfish.

"Twas kindja talking to itself, bout getting rewarded, and fooling someone. But it was paddling for all it had, like it was being chased... But I was kind of in and out of it..."

Galingal, you hear a faint splash and see some ripples spreading, from the direction you and Stena came from.

((I think so, roughly. The ripples are our fishfolk scout, I think. Not sure how far apart we are though.

Or if the DM is playing a switcheroo and we are on different sandbars miles apart and are about to confront some other party of misfits! eek))