Using IntelliJ IDEA to convert from Java 6 to Java 9 (approximately 300 8.5" x 11" pages of code)

I'm new to Java & IntelliJ IDEA. I was recently placed in charge of some (~ 300 11" x 8.5" pages) Java code which used Java 6. I want to convert to Java 9. I would appreciate any input on the following questions:

1) Should I expect the configuration or settings file of IntelliJ IDEA Community 9 to work in the new IntelliJ IDEA?

2) How might I estimate the number of hours required to convert from Java 6 to 9?

Thanks so much