Manipulating recorded data

Lets say i want to create a plugin that eq’ed a track after it has been recorded. How is this done without playing the track and recording over itself? Is it feasible to load the entire track into memory, apply the changes, then dump the signal to a wav?

Depending on what you mean by “load”, maybe. The plugin formats and APIs that JUCE implements don’t support offline importing audio data from the host as fast as possible, so some sort of “playing” through the material will be involved if you want the audio in as it is playing in the host.