I was thinking more along the lines of The Jedi Academy Trilogy, where Luke figures out that he can prompt a sort of reflexive Force Push from Force sensitives by probing their most distant memories (or something like that, I don't know, it's been a while). There was a guy in that series who "impossibly" escaped some sort of cave in or something as a child too, and Luke used records of that event to identify him as a possible Force sensitive. So it's not unprecedented in the EU for Force powers to manifest without training or even prior knowledge of the Force, when placed in life-threatening situations.
The "I understood the Force" line was meant more along the lines of he understood the Force was a part of himself, that there was an aspect of himself he'd never experienced before, and that it connected him to his surroundings in a way he'd never realized before, not that he "knew how it worked/could do cool stuff now". That, plus he was trying to make a point to "your folks" that they weren't going to be able to "think hard" and figure out Lorna.
As for how powerful he is (or was a that moment), I've always thought of him as fairly average. I've always thought that the best way to explain the different ways people write about the Force is to imagine that Force users experience their connection to the Force in different ways, so Timothy's whole "the universe sings to me" deal is a very personal description for him, not a claim to some stronger connection than others have.
