Yes it was-
try reading it. The chapter "Flotsam and Jetsam" shows evidence that Saruman had been meddling in The Shire for some time.
That...isn't what happened.
Again, try reading the book.
The whole point of Saruman's revenge is its pettiness, because that shows how far he has fallen, and makes a final point about the corrupting influence of a lust for power, which is one of the major themes of the entire Tolkien myth cycle. The key moment comes when Frodo won't have Saruman killed, because he pities him, and Saruman is enraged and humiliated at being pitied by such a meek and humble being.
This is all made quite clear in the book...
That comment is so bizarre that I don't really know what to do with it.
Firstly, you seem to be confusing Saruman and Sauron. They are different characters: check out the movies if you don't want to read the books.
Secondly, Saruman's coup in the Shire is not merely a revenge attack as such, but an attempt to grasp at any thin straws of power that he can. By this point, he has fallen from his lofty position, but remains obsessively proud and hungry for power. The Shire offers him the opportunity to be a big fish in a tiny pond and, given his reduced circumstances, he grabs at it.
Thirdly, an important point is that much of the damage is done by (paraphrase) "stupid Hobbits who only want to be important". Tolkien is making a point about the petty officialdom which followed England's victory in WWII, after which the state absorbed swathes of industry, commerce, infrastructure etc. In Tolkien's mind, England was aping its defeated enemy, which is just what happens in the Shire. He is also making a broader point about the heroes in a war rarely being the ones to enjoy the peace that follows. Though the Shire is somewhat repaired, Frodo remains estranged from it, and never really gets "home".
I can only assume they are being tongue-in-cheek with those comments. 
