What I understand so far:
Wrecking - to trash/destroy/be destroyed
Wracking - to be tortured, possibly from variant of "rack". http://www.etymonline.com/index.php?term=wrack also seems to mention that using the word "wrack" in the sense of torture is a mistaken usage.
Wreaking - "wreaking havoc" is the only example I can think of that uses this word, and it was apparently used in a similar manner to "wrath" archaically. http://en.wiktionary.org/wiki/wreak
What I want to find out:
The 3 etymologies seem to all be linked to "wrecan" via divergent evolution, but how closely linked together are the etymologies of these 3 words, and how did the final one, "wreak", end up sounding like "reek"?