To answer your questions:

1) The top line in the image says "Local structure type (how links are
saved)". I assume this was a rhetorical question but I do not know what your
point is. 

2) All of it is unclear, especially what "xxx" signifies. 

If you know what to do to achieve what I want then it would be mature of you
to tell me please. Please appreciate that what may be throughly familiar to
you is unknown to me and others new to HTTrack. 

On reflection it must be possible to save all pdfs in one folder as I have
already saved some like that but for some reason they save with a number
rather than the original file name. I want to save them with the original file
name please. 

It would be great if you could be nice and simply tell me how to do what I
want rather than just giving me very terse cryptic clues that do not help
please?
Thanks.