SMART= (in AmE) intelligent, clever. He talks about "your smart mouth" because he is transferring to that part of her body all her clever playing with him, her teasing. He wants to kiss her but she plays hard to get, that's why he focuses on her mouth when talking about her game.

DRAWING ME IN= Attracting me to it (to your mouth) = wanting to kiss you.

KICKING ME OUT= Rejecting me, not letting me get near you. To kick is, literally, to hit someone with your leg.

GOT= You've got. The sentence "got my head spinning" means you make me feel confused or overexcited.

SPINNING= Turning round and round. If your head is spinning you feel dizzy or confused or shocked.

NO KIDDING= I'm serious, I'm not joking, what I say is true.

PIN DOWN= If you pin somebody down, you win the fight by pushing them on the ground so they can't move (usually by sitting on top of them and holding their hands tight against the floor or some similar position). In this case, like most things he says here, it is a figure of speech, a metaphor.

GOING ON= Happening. The sentence "what's going on in that beautiful mind?" means "what are you thinking?" or better still, "what are you planning to do?".

MYSTERY RIDE= A mysterious journey where you never know what is going to happen next. An allegory meaning that life with her is like living an adventure.

DIZZY= When you feel like your head is turning round or feel confused. In this case because he is so in love that he can't think properly or understand what is happening, especially since he said that life with her is like being on a magical mystery ride.

(I) DON'T KNOW WHAT HIT ME= I can't understand what happened to me, or I can't understand why I made this decision (choosing you when all about you is a mystery).

I'M OUT OF MY MIND= I'm crazy.

ALL OF ME= My entire self, all my being.

YOUR ALL/MY ALL= You/me completely, 100%.

BEATING YOU DOWN= (metaphorically) destroying you, hurting you, fighting against you and winning.

I'M AROUND THROUGH EVERY MOOD= I am here to support you, to help you and be with you in every situation, when you are happy, when you are sad, when you are angry... in every mood. Your mood is the way you feel, your temper.

DOWNFALL= A sudden loss of position, health or reputation. "You are my downfall" means you are going to destroy me (or rather, destroy my ego).

MUSE= Inspiration.

RHYTHM AND BLUES= A kind of music, often romantic. This song here is actually "rhythm and blues", so it’s like saying “you are my song”.

RINGING= If something is ringing on your head, you hear it and hear it inside your head and you can't stop it.

CARDS ON THE TABLE= We have our cards on the table. It is a reference to a play of cards, poker in particular. In a game of poker players try to fool everybody else, but at the end, when they put their cards on the table for everyone to see, the truth comes out. In this case, both lovers were playing a game, but now the game is over and they both show their real feelings... and "we're both showing hearts", which means they are both truly in love. "Hearts" is one of the four suits of cards (hearts, spades, clubs and diamonds), and here it is used as a symbol of love.

THOUGH= Although, in spite of being..., but.