What are good indicators that a co-worker is flirting vs. just being friendly?

Here are some examples that gave "suspicion" of potential flirting -

*He always finds stuff to talk about with me. Even little, pointless things. It's like he absolutely HAS to talk to me.
*He has started randomly using my name. He will say my name to get my attention, randomly use my name in a sentence when it wouldn't truly be necessary to use my name, etc.
*He looks my way a lot. I will look up and catch him staring directly at me. He typically looks away quickly once he sees me look, but sometimes he will keep looking for a few seconds before turning.
*He seems fidgety. He will adjust his clothes or mess around with his hair a lot. He also whistles a lot randomly when I'm around. Recently when we were cleaning up, he walked by me and randomly sang a verse of a song on the radio (he typically doesn't sing to the radio at work - he might whistle to certain songs but not sing).
*He makes direct eye contact when we talk and tries to hold/keep my gaze/attention.
*once he was working directly with me on something and he walked by me and said "huh?". I didn't know what he meant, so I said "what?" and he was like "Oh, I thought you said something". I said no, I hadn't said anything.
*He started wearing cologne and seemed to want me to compliment it. He came over and said someone had said something about it and kept saying he thought it smelled good, so I took the bait and said it smelled nice. He seemed happy with that and made sure I knew what it was called and got me to tell him what I wear too.
*He asked my age. I overheard someone asking him how old he was. He told them then came over to me and told me that person was wanting to know how old "we" were. I knew they hadn't asked "US" anything. It was JUST directed at him. I simply overheard it. He said they told him he looked young then asked me how old I was. I told him and he said what he would have guessed.

So does that sound flirty? How can you tell the difference between true flirting and just being friendly?
What are good indicators that a co-worker is flirting vs. just being friendly?
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