There are two separate issues that you have asked about.
Satanic Verses is a book written by Salman Rushdie. I have never read it, but have heard it described as pornographic in nature. This has nothing to do with the fact that some verses were abrogated from the Quran.
Some verses have indeed been abrogated in the Quran. This fact is well-known and well-documented. There are 3 modes of abrogation. These modes are:
- Both the recitation, i.e., the text of the verse, as well as the command contained in it were abrogated.
- The recitation, i.e., the text of the verse was abrogated, but the command contained in it was not abrogated.
- The recitation, i.e., the text of the verse was not abrogated, but the command contained in it was abrogated.
When a verse was abrogated in text, it is no longer recited while reciting Quran.
When a verse was abrogated in command, it is no longer acted upon while living as a Muslim.
Both aspects of abrogation (text and command) are matters recorded by the Sunnat of the prophet.
Some might wonder what was the logic in abrogation. If the Muslim contention is that God is perfect, then what was the purpose behind abrogation of verses.
What I've understood is that firstly Muslims believe in Allah, not only in His existence, but also in His status as the primary authority to be able to define what is right and what is wrong.
The Islamic view regarding the purpose of creation of human beings was to test which of us would be obedient and which of us won't be.
The ideal Muslim "listens and obeys" Allah's commands.
Abrogation presented a test of faith for the people present at the time when the verses were being revealed.
Another purpose of abrogation was as a reminder of Allah's Mercy, where the text of a verse was left in, but was no longer acted upon, so that people may remember that initially, they had to do something, which they no longer needed to, after Allah was Merciful to them and lifted a burden.
There is a very well-written article on this matter, which I have essentially summarized above. I urge you to read it to gain better understanding.