I always encourage album artists to submit their track to the OCR panel for evaluation independently. You don't even have to wait until the album is released; just mark in your submission email for which album it is, and staff will take care of it.
With regards to your other question, the album director(s) get to pick a handful of tracks (usually 5) for the mixflood that will be posted to promote the album. These 5 tracks will be vetted by OCR staff (they have to meet the bar of course) and typically will be published in 2-3 batches in the first week of the album. Any other album tracks that you see getting posted are always individual submissions by the artists themselves; as album directors we only choose the handful of tracks for the mixflood. As always, what tracks get posted when is up to OCR staff discretion of course.
And to answer the unasked question: I don't know yet which tracks we will select for the mixflood We will do our best to select those 5 tracks that we feel represent the album and the game best, and of which we think they'll promote the album best, but since not all tracks are done yet and me and Trism haven't discussed this yet, we don't have a selection narrowed down right now.