Masha'allah - brother Ansar posted before I even pm'd him! Jazakallahu khair bro!
Regarding using an Arabic word search, its possible (thats how I usually do it) but its difficult and you need a decent understanding of Arabic to be able to differentiate between words (Arabic is an inflective language, so many words are similar with the same root, but can mean completely different things).
is the best out there, but this one requires a very good understanding of Arabic to operate.
I used it and I'm pretty sure its found me the 12 mentions of month, but my Arabic isn't that strong so I'll need to check it with someone whos Arabic is stronger. I'll post all references when/if I work it out insha'allah.
As fi_sabillilah said however, these are nice little signs in the Quran of its validity - there are plenty, but to concentrate on them however would be to miss entire point, as the once-kick-ass Bruce Lee said in a very cheesy kung fu movie with bad dubbing and really bad English: -
"It's like a finger pointing at the moon..if you concentrate on the finger, you'll miss all the heavenly glory" (don't ask me why I know it off by heart, it just stuck :p).
Its true though, the message of the Quran is THE most important thing, don't get distracted with the arguably insignificant aspects of the Quran such as this.