NYS Thruway has an excellent website with variety of Traveler's Information, including alerts, updates & weather forecasts, current road conditions info for its entire length from NYC to Buffalo. Bookmark it & check it on the morning of your departure from your hotel, and you should be fairly well prepared. Google Map it and a virtual road driving trip will give you a good feel for what it's like to drive on it.
http://www.thruway.ny.gov/wtas/netdata/
If there are last minute changes, hazardous conditions, alerts & electronic signage at the Syracuse toll plaza before getting onto the Thruway will warn all drivers of what's ahead & options.
Full service rest stops with gas & food are spaced every 30 miles or so apart, and it's advisable to take a "safety break" and rest every 2 hours as the Thruway portion of the drive can be boring, miles after miles, leading to fatigue and tired/sleepy drivers are most at risk and prone to going off road and into the ditches.
As for Rt. 380/81 North past New Jersey into PA, then back to NY via Binghamton, NY area up pass Cortland, to Syracuse - ice & snow shouldn't be a major problem - Rt 380 and Rt 81 to the N.Y. State line are fairly hilly in places and could be slippery, but a well equipped RAV4 driven with care should be fine - maintain plenty of safe distance behind those truckers or 18 wheelers as some of them could have trouble "climbing" the slope when it gets icy and windy in snowy conditions.
The problem sometimes is when you are caught in lake effect snow and/or blizzard-like, near zero-visibility driving conditions, the 2 lane highway is reduced down to a single passable lane and if the vehicle ahead of you stalled, everyone behind cannot go around it depending on the amount of snowfall and accumulation. Even for AWD/4WD vehicles in the hands of an experienced driver, equipping all 4 tires with dedicated snow tires and not the "all season radials" is the preferred way to go, stop, turn and brake and avoid spinouts.
Highway snow removal crews in these area are very good in clearing and reopening the roads within a matter of hours. Thruway segments near Rochester, NY and Buffalo, NY are the most unpredictable in terms of blizzard conditions that's been known to stall all travelers over the years - just make sure you carry spare water & energy/food bar in your rental vehicle in the unlikely case the Thruway is just down & you are "stranded" in traffic.
Check & ask the car rental place for a snow brush (free, if available) and check that the windshield fluid is fully winterized and fill to the top, and, happy winter driving.