Hi Gorilla,
You might want to do a little bit of a research on "Re-entry" permit. The simplest definition is
"If you are going to be out of the US for more than a year as a Legal Permanent Resident you need to apply for Re-Entry permit".
If you are planning on applying N400 in the future, the long break might have an impact...
Please read more on the subject...
Good luck in your endeavours....
V!