The cura version you seem to be using is old. Get the update and try the experimental Tree supports. It is is fantastic. You need to just sand the interiors. You can also use XTC-3D Smooth on. Works great for post processing.
Those holes do not appear to be self supporting, so I would think that you would need support inside of the holes and in the internal tube. As @singlefonts mentioned water soluble support is great for use cases like this where scraping out support from a small enclosed area can be difficult.