Hi, 

I think this depends on what you think of as a backup. FME is able to read features and copy them over to another table or another file format. It might be able to copy the whole table without reading it with the sqlexecuter but I would need to look into it further.

Yes, there are many options to use FME to perform a backup of a database or table. 

with the SQLExceutor you can essentially perform any operatoins which you can via SQL.

You can also make system calls with FME using the SytemCaller. This is nice if you already have a script which runs a backup which you’d like to integrate or if you want to use the psql.exe directly.

Probably the easiest method it what @birgit suggested which is to just read/write all data though FME. 

 Here’s some more info from another user who had a similar question.