- can all the layers in a drawing be shown in a tabular form ?
another table than the Layer List? I'm afraid no.
- and edited ?
no table, so no edit, except in the Layer List
- is there a method to set a specific attribute to a nominated value on all layers in the drawing ?
Not inside LibreCAD I think.
With some hacker skills and DXF knowledge one can do a search/replace in path, DXF is a simple ascii format text file. But without care, this can make DXF files unreadable, so be sure to have backups before running a search/replace tool.