Is my coworker just being flirtatious?

I like this guy and he happens to be one of my coworkers. He’s a very outgoing person and is very confident in himself. He is flirtatious with me and other people but everyone at work says, it’s different with me. He seems to tease and play fight with me all the time. He insults me but I know he’s joking. If i get hurt by one of his playful insults he appoligizes right away. We sometimes get into these 5 min long staring contest where we just smile. I usually turn away first and blush and all he does is smile back at me. Lately he’s been asking me what my plans are for the weekend and for my holidays. And then there’s his personal space, if I were to be shoulder to shoulder to him he wouldn’t move, and when he get’s into my personal space I don’t move either. I’ll be doing some prep work in the back and he’ll come up right beside me and just stare at me untill I look up at him, I ask him “what” and he just smiles and continues staring. He likes to get my attention, i don’t know if this means he likes me but he’ll say something funny, or something loud and wait untill I look up to see what’s going on and if I don’t he’ll do it again. The one time he put his hands behind his head and it looked to me that he was flexing. I didn’t look up at him and he got a little upset , he pulled a muscle standing there doing that for so long. I thought it was cute. My cooworkers know I like him and think he likes me back. I work at a fast food place (oh yah) but our prep list get’s pretty long sometimes, bruchetta is one of the things we have to do it’s time consuming. (if you don’t know what bruchetta is it’s tomatoes and onions diced together with oregeno salt and pepper and garlic powder all mixed together) anyways this takes alot of time to prep and my coworker hates doing it, when anyone else asks him to do it he says no, but when I ask him he does it. And once I was off at around 3:30 and he asked me to stay and help with prep. So I started to do some and everything I started to do he said don’t worrie about that I’ll do it. I ended up just sitting there talking to him for a couple hours. The thing that confuses me the most was there was this one time I left work early to catch my bus. I came in the next day and was talking with my coworker crush he was in a bad mood because he had to work with this guy jake again. Jake is a really slow worker so it’s hard not to want to strangle him. But I asked my crush what was wrong and he said he didn’t wan’t to work with him because he would have to talk to him. I was confused, I asked him why he didn’t want to even talk to him. He said he was mad at him because he insulted me. He said he was pi**ed off that he insulted me. He said he didn’t talk to jake all last night after what he said. I was flattered, that he would stick up for me like that. Do you think that is a sign?

What I’d like to know is if you think he really likes me or because he’s a regularly flirtatious guy it’s just him being himself? I really like him and i would love anyone’s opinion and advice.