All of those concepts are defined within perception (or "consciousness" if you prefer). "Everything" and "knowable" are, I think. Even metaphysically, it's hard to know what you would mean beyond our awareness.
I see what you mean, Daniel, but I don't think we need the notion of perception in order to make statements like the one I formulated. There's a difference between wanting to have answers to certain questions with the help of perception and 'stating' (with the help of some reasoning) that you will never (all) the answers.
As for the usefulness of knowledge, I competely agree. We should try to know everything that is 'knowable'.
Btw, could there be anything outside/beyond time if time were non-finite?