1) It is not landlocked; Locke City is by the sea!

2) That is correct. Things like the pink light in the sky before April 1st and onward - that she could conceivably have had contact with - are fair game for kicking off an initial Echo.

3) That would probably be okay. After all, the characters here are reincarnations, so there's nothing particularly binding in them having to be their canon age. A little fluctuation is a-okay.