iCloud/iTunes Match and metadata

I'm (obviously) going to be paying for an unlimited iTunes Match account. I still have a lot of music ripped from CDs that I later sold used that's at 160 or 192 bps, so iTunes Match is basically just a cheap way to upgrade all of that music.

What I'm really curious about, though, is how iTunes Match and/or iCloud will deal with metadata. I invest inordinate amounts of time in getting the tags of my music files just right. My genre system doesn't map to iTunes, exactly, so does that mean that iTunes Match won't be able to match those songs? Also, what if I change a song's metadata (id3 tags)? Will that music file be re-uploaded to iCloud and then downloaded to my other devices?

Finally, what about playlist syncing? This is my number one most desired feature. I want to be able to make a playlist on my iMac, and then be able to match it exactly on my Macbook Air--and use a playlist as an algorithm for what music gets synced over, since my MBA get hold my entire collection.