To summarize the DistroKid experience, it got the "music from Major Stryker" album on iTunes within a few hours of my uploading it to DistroKid.com. Spotify came through in a few days. Google Play and Amazon took 2-3 months. So I say the jury is still out. I will be uploading another album before long, and I'll post my experience here. DistroKid has only been around for a few months itself and it's a one man operation.
My question has been answered in the DistroKid FAQ about uploading one song from an album and wanting to upload other songs from the same album to go with it later). You delete the "album" of the one song and re-upload that song along with the rest of the cuts on the album.