Readings & Meanings:
You need a valid pass to get into this building.
That kind of thing is impossible.
There are many benefits open to you if you are cute.
口 is the radical.
The pictogram shows a mouth and a bent hook. The idea is that it's hard to speak with a constricted or bent throat, but it's "possible." (Or so Kanji Networks tells me.)
可愛い is the original kanji of かわいい, yes. But it's become very common to use the hiragana.
Hiragana is more "friendly," also. Writing かわいい as 可愛い makes me think of Gore Vidal chatting someone up using eight-syllable words. It's correct, but just too stiff.
That being said, isn't 可愛い such a cute combination? Approve + Love. When you say かわいい, perhaps it's like approving someone's/something's loveliness?
This is the top result from Google's Video search for かわいい: