For long visits outside of the US, (>6 mo), you would want to get a returning resident permit. I'm blanking on the name of the form just now, but someone else will mention it. You have to apply for it from within the US, and appear for biometrics.
Long periods outside of the US as a green card holder can definitely impact the timing and your ability to naturalize. You will want to keep very good records of trips, and adhere to the residency requirements.
In terms of your ability to safely travel and return to the US - no one really knows, at this point. Everyone will individually have to assess their own tolerance to risk while closely watching the EOs and US immigration news and trends.