The problem with trying to figure out how someone feels about you is that you can never be sure and so many signs can be taken both ways. I will try to answer this as best as I can and hope that you can figure it out. Maybe all you need is a confidence booster, but you really should just talk to him and be open and ask him how he feels, or better yet, let your mate know that you like his friend/ ask if he knows whether he's interested in anyone at the moment or not, and if he thinks he'd be interested in you...
- stiff and awkward= normally good. It might mean that he just doesn't know how to act around you... If he likes you he might not want to do something 'wrong' so might refrain from doing anything at all. Normally especially if he is 'awkward'. The only way it woudl be bad is if he knew you liked him but he didn't like you and so he felt awkward around you. Don't think so though.
-stealing shy glances at me= Also normally means he likes you.
-He agrees with some other of my opinions too.-> if a guy will change his oppinion or contradict himself to agree with you, it normally means he likes you. if he was chidding his mate cause he was innept, take it as a good sign as its another way for him to show off- by making fun of someone for not being able to do something impressive he is impressing you or anyone around by saying, in other words, that he can. Also if he is often willing to contradict himself and swallow his words, he probably likes you as that can be a tough thing for a guy to do.
- Another time he called me good girl smiling at me.= As for the phone, smiling thing- if he was to like you, he would be happy to have an oppertunity to play the knight in shinning armor and sweep to your rescue, he'd want to be able to have you need him; its a primal instinct. as for the teasing thing, well I've had guys that I both, get along with well as friends, and that liked me, call me and tease me in such ways. Heck! I've even teased guys that I liked saying things like "Who's a good boy!" Or "Ada boy!" like I was talking to a dog.
I dont know what to say about the weird expression. I often have to strech when I've been sitting down for a while, or after a lot of exercise or dancing the night before. As a dancer I'm rather flexible, and like you, I don't generally have much regard for other people when I need to stretch. It can be soo uncomfortable and I just need to do whatever I can to get comfy again! I remember on one particular six hour train ride, I needed to crack my back soo badly but had no way to do it except to slide all the way down my seat so that my back was making a right angle, and I slide farther down each time to crack each verdibrae. I got a lot of weird looks. In fact, whenever I so much as sit on the floor with my legs spread to a point that wouldn't even be near a stretch, or even with my legs 'criss cross apple sauce' I'll get strange looks because such flexibility is just... astounding for men. Also, it can be quite a turn on, or so I'm told. Seeing a woman stretch, and expose her self, in a more vulnerable state, can really affect guys for some reason. I'd take it as a good sign.
Good luck in all your endeavors with this.. footballer :)