You pronounce baca incorrect!
C is always a ch sound not a k sound
Would "Baca yang keras" be acceptable?
I don't think so. You use yang that way to differentiate between things. You use dengan when you are applying an adjective to a verb, like 'bicara dengan baik' (speak well). Disclaimer: I'm not an expert, just my observation so far.
It would be acceptable in daily slang conversation.
But in written grammar it would be wrong.