You can test that you are able to access more RAM by setting the minimum and maximum memory being used, e.g. set min=10GB and max=20GB. Then check usage. 10GB might be a high minimum but if the server is only handling SQL Server then it may not be. Setting a realistic minimum means SQL Server will not have to waste resources claiming more memory as it needs it.
AWE enabled is completely and totally ignored on 64-bit. It does nothing, it's essentially a no-op.
Enabling AWE will not have any effects at all on 64-bit. It's locked pages that the blog post says can have a performance improvement (service account added to the lock pages in memory local security permission)
Well, sure ...if you are going to read the ENTIRE article it's pretty clear thar AWE is a no-op; especially the part where they say that "It is a 'no-op' for 64bit SQL Server systems". But reading the ENTIRE article is tantamount to cheating...
======================================= Faced with the choice between changing one's mind and proving that there is no need to do so, almost everyone gets busy on the proof. -John Kenneth Galbraith