Digital tape is not easier to edit per say, but does allow 48 tracks instead of 24. This allows them to do overdubs and punch in corrections without erasing the original. It is highly unlikely that they would copy the digital tape back to analogue. Taking recordings down extra generations for the sake of it is a very recent trend. Another cool thing DASHes would do is allow you to do real time comp tracks without losing quality. So like, if you have a live background vocal that's a little out of tune on one note, you can record a replacement on another track, then comp them to yet a third, using ONLY the needed replacement note. This comp is done entirely with the internal digital architecture of the tape recorder and aside from a 10ms crossfade, the results are identical to the original.
I cannot speak for the CD vs. vinyl mastering process because that would require buying both and comparing, or at the very least, getting to know the mastering engineer personally. Most likely, it was mixed to digital stereo straight off the 48-track DASH to stereo DASH, then mastered to whatever the acceptable digital medium of the week was. A glass master would have been made off of that and most likely the lacquer master as well. The "proper" way would be to make the lacquer master directly off of the mix tape, but your guess is as good as mine on whether or not this was done. If the latter is true, you can expect a slightly more natural sound, but that's not a guarantee.
On Steely Dan, I believe their preferred method is to record on analogue, then make a digital slave. The slave is used for overdubs and the final mix is done by locking the slave to the original and using 1st generation tracks as much as possible. I don't follow them, so don't quote me on that.
One more thing about DASHes. You can fly tracks onto a second machine, then back to a different part of the source tape losslessly (is that a word?). This allows you to take, say, a guitar riff that was done better in the second verse and copy it to the first verse. There's a lot of cool tricks they allowed before MDMs and DAWs were the thing to use.