Do you think they would really go for Kiev? I mean as you said Ukraine is a huge country and they could never conquer it. They could destroy yes but that doesn't serve their purpose.
Their Navy is very capable but has not been used so far or much according to the information I have seen.
Yes. Its clear Putin wants the entire country and views his quickest path in getting there is through a decapitation strike of the current Ukrainian government. He's doesn't appear interested in "just" taking southern parts of Ukraine and allowing a democratic Ukrainian government to remain intact in Kiev.