The prop guards can affect the collision avoidance, they make it rather large and unwieldy too - more prone to being affected wind.
Don't see much need for them unless you plan on flying exceptionally close to things. 

The camera will cope without ND filters but it's something to consider getting later.
If it's very bright especially like sun on snow, slowing the shutter down will make the video look smoother but there is almost always a hint of color cast.