>1) Suppose I specify EditWork, SortWork and ProgWork for our main application. TMPFILES will be left default. Now, how can I determine, what are SortWork, etc. settings?

You can't really, AFAIK. There's no function. You can keep watch on the directories you designate and see if files start appearing there.

>3) How much space I need on this drive?

The help for Sort (which would be pretty much similar in the way it moves content around) usually says the space needed is about 2.5 times the size of the table. It probably doesn't copy the unused memo blocks, so this would make it a little less then.

>4) I prefer to leave TMPFILES as set by user, but adjust SortWork. Would it mean, what now each index command will use this directory? If it would be a NetWork drive, how it would affect the perfomance?

Probably some internal files used while indexing and/or SQL may go there. You may create a separate app with a timer wich would recheck each of the three directories while the main app does what it does, and do some logging with it.

> My manager wrote me a letter: Create temp directory on a Network drive for this application. You can see, how many complications this simple proposition is led to...

There are no simple problems when it grows this big... only simple solutions, if you're lucky.