I've heard different things - on the one hand saying things like 高いか, きれいか, or 飲むか is too aggressive, but in my grammar book it says that か is used with informal forms. Furthermore I'm told that instead of using か with informal forms, one should simply slightly raise one's voice.
Finally, I've heard questions simply asked by using だ, such as in それがどういう意味だ? or 何だ?
I'd appreciate some clarification. Thanks