RUI MEIRA  totally agree with you !! I coudln't be more satisfied and happy when I found and saw this app working ! really amazing ! I was thinking in buying a Networked Media Tank, then I discovered PS3 Media Server...didn't even try any other app because this gives me anything I could want and for free ! I'm thinking in donating something because they deserve it :)  
(Version 1.10.5)

RUI MEIRA  Hi Mr. Ash !

I've tried PS3 Media Server this weekend and I don't agree with you in any of thebehaviours you described, so I'll try to help you.

1. I've watched several .mkv files and I think you might not be able to do it because you should be using wireless connection, and it can't have a transmission rate high enough for HD, so you should connect your mac and your ps3 with cable to the router. I've tried a P2P connection and it didn't work out.

2. You can access your itunes library, what you have to do is just to add the folder ".../Music/iTunes/iTunes Music" to the shared folders. Then, all your music will be available by artist/Album/Song/etc. What you won't have is your playlists.

with some search you'll find several free and paid applications for this purpose, I just tried this one and loved it ! Hope this will help you out !  
(Version 1.10.5)