Now then, lets discuss the whole point of the OP.
From the leaked redditor a few weeks back, he confirmed Aqua and Topaz and said that Steven will end up at homeworld by the end of the bomb.
When I first heard about stuck together I assumed it was the townies stuck inside a jailcell on the way to homeworld, but it may now mean they're literally stuck together on Topaz.
The trail is probably Steven facing trail in homeworld, perhaps even in front a diamond and thousands of gems.
Off colors is what Holly refereed to the beta gems during the zoo arc, so I'm assuming this is takes place at the zoo.
Lars head could be the same, Lars is in the zoo with the other captured humans and perhaps Steven takes over his mind again.