first of all, yea sure its possible, how easy depends on your knowledge and determination. way too time consuming for anyone to give you a step by step on how to do it and not confuse you with jargon and a 100 different way to do it as well.
I use serviio as a upnp/dlna media server which will handle all your music/video/photo
I also use subsonic for a decent music web interface.
Installed on ubuntu server, but doesnt have to be.
have a google as i dont have time to explain as im procrastinating about going for a run in this pissing down rain.
top tip generally wireless sux, make sure your server is conected via cable not wireless, your devices like phones/ipad can still be wireless though.
slight edit, if you want to control all this via itunes then im not sure if this will work, but would never use itunes anyway, too limited