As to the first bolded sentence: In the 1970s, statutory interpretation was very loosey-goosey. Judges would look everywhere except the language of the law first. Scalia changed all that. Now, basically every judge in America is a "textualist." All statutory interpretation begins an ends with an analysis of the language itself. He's co-authored incredibly influential books with Bryan Garner on the subject. Even Justice Kagan has basically acknowledged that he completely changed the field and considers herself a "textualist."
As to the second bolded sentence: He wrote this opinion --
Employment Division v. Smith - Wikipedia, the free encyclopedia
The reason why the First Amendment does not protect religious people from neutral laws of general application is because Scalia wrote that.