A question about 了 and a verb 挂 Below is a list of sentences. Some might be a bit strange, but I would like to hear a way to mend them using only 在着了 and other such particles (i.e. no time words and other adverbs).

Is my translation right? 


墙上挂一幅画。-"Picture hangs on the wall" as a rule, usuall it does.
墙上在挂一幅画。- "Picture is being hang on the wall", the process of hanging is not yet over.
墙上挂着一幅画。- "Picture is hanging on the wall", as a result of being hanged in (3).
墙上挂了一幅画。- "Picture IS hanging", i.e. the picture is indeed as a fact reality is hanging there.
墙上挂着了一幅画。 - ??? i'm stuck here...
1.墙上挂一幅画


Just a neutral description and the meaning is context-dependent


  2.墙上在挂一幅画


Your translation is correct


  3.墙上挂着一幅画
  
  4.墙上挂了一幅画


I don't see any difference.Both means "A picture is hanging on the wall"


  5.墙上挂着了一幅画


This is gramatically incorrect and doesn't make any sense