1. No it can't, there is another thread where this was attempted and failed, you can search the forum for this thread
2. There is an included fan bracket that can be mounted for the bottom M.2 slot for active cooling
3. I connected a 40mm Noctua PWM fan and just set it on top of my Video card in front of the top M.2 heatsink and reduced 960 Pro temps 5 to 10 degrees at idle alone. my Video card is AIO cooled and runs very cool
4. The included fan bracket with a not included 40 to 50mm fan, which is designed for the bottom M.2 location can probably be mounted for the top M.2 location as it connects with a motherboard mounting screw
The heatsink on these boards is the best I have seen but some kind of airflow is required if temps are a concern and #4 above is the best option for cooling and aesthetics