I would deal with the cooling system first and leave the Vanos for when it gets warmer. The Vanos is a 4-6 hour job by itself. While removing the fan is redundant to both tasks and is often the toughest part of either job. If you put a dab of antiseize on the fan clutch during the cooling job, future removal will be very easy.
Your lack of heat could be anything from air in the system to aux pump motor to heater control valve. Air bubbles are usually due to some cooling related service. If you have had no recent cooling system service, you can eliminate air bubbles as a cause. The overheating is more likely be due to thermostat. Although you have relatively low mileage (78K), it is better to replace the complete cooling system in order to restore 100% confidence against cooling system failures (which can be fatal to engines). If you do it all, don't forget the tensioners and belts.