Tagging issues between Itunes and Slimserver DB's

I got my music fairly well tagged.  Slimserver DB was looking pretty good.

Having just obtained an iPod, I have tried to import my library into iTunes.  
As I understood it, iTunes reads tags from files and stores in an xml file.  I 
decided to keep my iTunes library folder separate from my music source folder, 
and add the folder into iTunes.  I didn't want iTunes mucking up my music - 
reorganising source files, changing tags, etc.

I have some issues:

1. Half my music is FLAC, and I am generally replacing older rips that I have 
in mp3 format to FLAC.  iTunes doesn't support FLAC, and I don't really want to 
hold two copies of everything, so I am investigating some iTunes replacement 
apps.  I've seen things mentioned about anapod explorer and a couple of others 
in the past.  Can anyone recommend a decent replacement (generally I only need 
something that I can use to sync music to my iPod - I'll use Slimserver to play 
music in house, and foobar to play on PC).

2. I have some albums with multiple artists, but also tagged with ALBUMARTIST 
to keep the songs grouped together under that artist.  In iTunes, the songs are 
split across all artists.  I fixed this in iTunes by selecting Compilation=Yes 
for all songs.  However, upon a rescan of slimserver, the album has now moved 
into Various Artists.  What's happened is that iTunes has stored 
ITUNESCOMPILATION tag for each track, and slimserver seems to prioritise this 
over ALBUMARTIST.  Is there a way to prevent Slimserver from reading 
ITUNESCOMPILATION, or a way to get iTunes to not require ITUNESCOMPILATION 
(i.e. group by ALBUMARTIST)?

3. I have always tagged multiple artists using a ";" delimiter in one ARTIST 
tag (and likewise for ARTISTSORT).  As this doesn't look good in other 
software, I thought I'd try changing to use multiple ARTIST/ARTISTSORT tags 
(I'm assuming that if the two pairs of tags are entered in the same order, the 
ARTIST/ARTISTSORT relationship will still work correctly).  However, I tried 
this with one track and rescanned, and slimserver only displays the first 
artist tag now.  The track also has an ALBUMARTIST tag, so could this be 
confusing it?  I did a search in the forum for multiple artists, and I see that 
other people have got this working.  Before I change all my tags, are there any 
gotcha's?  Does other software generally cope with multiple artist tags?

4. I have used folder.jpg for most of my album artwork.  iTunes doesn't seem to 
find this, so I decided to fetch album artwork in iTunes.  This detected quite 
a few albums and brough back the artwork, but how does it store it?  Changes to 
tags seem to write back to the actual source files, rather than the iTunes xml 
file, but I can't see artwork embedded in the mp3 tracks, and I don't think it 
has added files to the music source folders.

Phil