I can't imagine why johnrodrigez72 is recommending a plagiarism factory to anyone! Plagiarism, including essays written by someone that another receives credit for, is dishonest and likely to fail in whatever its ambition is.

It may be that people spell it both ways, but that doesn't change the fact that "wrack" is a mistake for the original "rack," i.e. "torture." Racking your brain doesn't mean messing it up or wrecking it.

I don't think "nervous of" can ever substitute for "nervous about" in good English. "She was the most nervous of the three performers" is OK.

The only problem with "pretty" in this usage is that it is vague, like "kind of" or "sort of" (kinda, sorta). It's an empty intensifier, and appropriate only in informal speech. "Pretty much" isn't any better. "Somewhat" and "fairly" fall into this category, as well/

The idiomatic phrases are "in the long run" and "over the long term." "In the long term" isn't wrong, it just sounds odd to the experienced reader. If you care, go with the standard idiom.