[MMM]

かわいいだ　or 高いだ would never be said or used. It is incorrect. だ never follows a ~い adjective.

かわいいです or 高いです are perfectly normal, everyday sentences. Just like in English, adjectives can come before nouns [　それは高い車です。] or stand alone.　[ その車は高いです。]

かわいいですね。 and 高いですね are also good sentences looking for agreement from the listener. The speaker assumes the listener knows the information already.