A nonrestrictive clause is also known as a nonessential clause, and I like that term a bit better, because it more accurately conveys the idea behind the function of the clause. Basically, a nonrestrictive (or nonessential) clause interrupts a sentence and brings extra, bonus information to the sentence that is not really needed to convey the core meaning. Most grammar texts indicate that a nonrestrictive clause begins with a relative pronoun (who, which, that), but your examples seem to treat this idea a bit more loosely—more of a general sentence interrupter. Consider this example:
Yellowstone National Park, which rests atop a supervolcano, features some of the most diverse ecology in America.
The phrase in italics is the nonrestrictive clause. We can lift it right out of the sentence, and we have a perfectly great sentence left and no loss of overall meaning:
Yellowstone National Park features some of the most diverse ecology in America.
It's nice to know about the supervolcano, but it isn't crucial to understanding the sentence. So let's apply that idea to your examples:
The comic books ranging from X-Men to Avengers were in mint condition.
The basic sentence here is The comic books were in mint condition. The rest is bonus information, so you should put commas around it:
The comic books, ranging from X-Men to Avengers, were in mint condition.
Next, we have:
I love all animals especially dogs and want to work at the zoo.
The basic sentence here is I love all animals and want to work at the zoo. The words especially dogs are bonus information, so surround that with commas:
I love all animals, especially dogs, and want to work at the zoo.
And finally, you have:
I had a dream once more like a nightmare about a zombie apocalypse.
The core sentence is I had a dream once about a zombie apocalypse. That sentence is interrupted with the words more like a nightmare, so surround that with commas:
I had a dream once, more like a nightmare, about a zombie apocalypse.
I hope this helps with the punctuation of sentences containing additional, nonessential information.