Thank you for a nice first post.
I think one or two of these posts float around somewhere, but there's quite some more in emails. Also about the other Mac players. Maybe Mac in general.
About the coverart and such :
Did you ever see what you see in the below screenshots ? But notice that this is not about embedded coverart. It must just be in the folder of the music (or a special folder for it in that music folder) and there it goes. All automatically. And with some options (I showed two). The size of all is adjustable (I made the second one of much smaller size; first one can be much larger as well). See where the mouse-hand cursor is where to adjust this.
In the second screenshot you also see that in the right pane all Coverart will be shown; the button "ShowData" a litte above the mouse-hand activates (red) this.
The third screenshot shows that everything can be in there as "coverart" and in this case the mouse pointer is at an URL. Everything can be asked for as well (double click) and in the bottom of this screenshot you see the web page coming from this URL.
Since Coverart can comprise of complete high resolution scans of booklets, they can not be embedded IMHO. The music files would be over twice as large at times (such a scan easily being 6MB and more), plus it is redundant. So, when it would be embedded and 20 of such scans had to be in each track, each track would grow with 120MB, the track itself maybe being 30MB (in FLAC). Thus, in XXHighEnd things go where they should be, and even for MultiVolume albums this is "normalized"; the general Coverart can be stored at the album level, and Volume-specific data goes to the volume (folder) itself.
In the fourth screenshot you see that rightclick on a Coverart Item in the roght pane shows a menu with some Coverart dedicated possibilities. Amongst that resizing while sustaiting the quality. So, the 6MB I mentioned before can also be 40MB because of someone who thought that really was nececessary to make the booklet etc. readable on-screen. In the mean time your disk is literally full because of this again.
Lastly for now, notice that what you see in the middle pane comes from the selected "music folder". In my case this is a Gallery, which is a derival (meta data) from other various folders and discs, and I named this one Nice Stuff (see first screenshot at the bottom). So, in the left pane that Gallery Folder would show up as Nice Stuff, and I can click it there while in the middle pane now its contents shows up.
Personally I hardly use the left pane myself, and always work from the middle pane only. So, there could be all my music from all discs, or a selection like Nice Stuff, or Drive G:\. At the one but last bottom text field I type for what I want, and when that would be Abdullah, all what contains Abdullah shows up in the middle pabe right away. So, that narrows down. Next I click the (or more) albums I want, and load them into the Playlist Area. From there we play.
Lastly, notice that what shows up in the middle pane can just as well be tracks only. This happens when you put individual tracks in a Gallery (never mind how for now), and it shows the same; the Coverart will all be there as you see it below.
Another means of getting track data (instead of album data) in the middle pane, is entering a T instead of the A you see in that little textbox left of the Search button at the bottom - followed by clicking that search button. Again all will show with coverart;
Would you have organized all such that all your music indeed is reachable from one root Gallery entry (folder), a search for all tracks may take a minute or two (in my case with over 300,000 tracks), but any result in the middle pane (Library Area) can be saved, and can be called for later by means of RIGHTclick on the little "puppet" button under the search button (which is also where a result is saved). This way, your 300,000 tracks show up instantly (0.1 sec), and all is available for hot-searching in there now (again, type into that one but last bottom textbox). Type love and all tracks containing love appear (but actually it is the folder paths containing that, so "Love" from the Beatles as the album will show up too with all its tracks).
Let me know whether this helps.