This may be a dumb question. But for example: how can I change hundreds of shapes in Metal1 to Metal2 in an easy way? I am using IC61. Thanks in advance.
Presumably the am_ft_not_low_ind is some derived shape (you'll have to see how it is being produced), and am is the original top layer metal. There's a good description of what the geomGetEdge command does with the coincident operator in the Assura documentation (in $ASSURAHOME/doc/assuracommandref.pdf) - there's a picture explaining it very clearly.
Without knowing the volume of data on each of the source layers in the command, it's hard to know why it's being so slow.