Hi, and welcome to the forums. I can't tell you how to report this stuff as I don't know quite what your assignment requires (and I wouldn't be willing to do too much even if I did know LOL). I can tell you however that it is common in most grammars to contrast canonical/unmarked word order with non-canonical/marked word orders, and to explain the functional motivations behind the variation. Essentially we are talking about how information may be packaged in different ways, given differing emphases depending on the word orders chosen, in order to achieve various stylistic effects. Examples (bolded) of marked structures are given in the abstract for the paper you've mentioned:
The main purpose of this article is to show that presenting certain important facts in the short stories using several marked syntactical structures in English (extraposition, existential sentences, pseudo-cleft sentences, passive, cleft sentences) is not at random because those structures have specific communicative implications as we will see with the analysis of the corpus of examples.
( http://www.jllonline.co.uk/journal/jlli ... ola3_1.htm
To take one such marked structure, the existential serves to signal that the thing being introduced isn't (at that precise moment, at least*) engaged in much more than existing/being introduced into the discourse (otherwise the predicate might be left much more open):
There's a bird in that tree!
A bird...in the hand...?
There's a spider in the bath!
A spider is...an arachnid? A source of phobia to many? Not pleasant to eat? What, exactly?
The structure essentially allows a new item (or new subject if you prefer, in that 'There' is a "dummy" subject), the item of focal interest, to avoid the "given" position (which is usually first, and/or "known"). Compare:
There's a lot to do (There=given, a lot to do=new, focus of interest)
*A lot is to do
Can there be life on other planets?
?Can life be on other planets?
For information on ratios of use (and for functional explanations, plentiful examples, etc), the corpus- and indeed register/domain-based (the smaller rounded up to instances per million words) Longman Grammar of Spoken and Written English
will be very useful. (There's also a student [LSGSWE] edition available, but it's obviously somewhat abridged/not quite as comprehensive). Hopefully your college library will have such resources, and you're allowed access to them. The relevant chapter in the full-size LGSWE is chapter 11, 'Word order and related syntactic choices'. The information on existentials alone covers 13 pages (well-written, reasonably digestible pages, though!).
*Note however examples like There were papers lying around all over the floor
, There was someone skulking behind the bushes
and Was there somebody standing there or was it a trick of the light?
(all from the OALD6).