It's a regular rubber gasket, I think it should be the same as on the 1.8T engines. Should be available in every normal part store (though I would suggest the victor reinz brand). Other gaskets you could try changing while you have the cover off are the cam chain tensioner gasket and the half moon seal. They however require a bit more work and possible fiddling.
Yes for AGN it isn't as simple as the inlet manifold runs over the cam cover, thus you either disconnect it completely and remove it out of the way, or disconnect partly and get another pair of hands to hold it a little bit up. It isn't too bad of a job, but you'll probably need a new gasket if you completely remove it and possibly something more.
For silicon some say not to use any on the cam cover gasket (if you have a rubber gasket), some say use it for corners, some say use it everywhere. I've done one where I used silicon everywhere (plus a gasket) and it has been currently holding for almost a year. So I guess it's whichever way you think sounds reasonable.