Indeed selection will be activate on space key press. This "by-design" behavior and there isn't built-in infrastructure to prevent this behavior conditionally. It probably can be implement, but it will scenario
Regarding your second question - I'm not sure how replicate the behavior. I've prepared small example - keyboard navigation and dropdown in Grid editor: http://jsbin.com/OjAWaJe/1/edit
The click on the dropdown expands it on the very first click. Can you elaborate on how to replicate described behavior?
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