Need some help stripping down a thrift bike..

[mtbdarby]

OK, I'm new to this bike mechanical stuff but I have time on my hands and not much money and I want to learn this stuff. So, I dove in today...

I found a bianchi road bike in the trash this spring and I want to strip everything off and sell the frame (it's too big for me - 58cm). I got stuck trying to get the chain off. I think I have the right tool but see the picture of how I have it on there. I have turned it as tight as I can but I can't get the pin out. Is there a right side or wrong side? I don't see any master link - they all look the same to me. My local bike wrench was going to stop by on the way home and show me how but he stood me up

The other thing I can NOT get off is the seat post. It looks like a square peg in a round hole. Whoever had the bike obviously replaced it but I can't pull the metal out enough on the frame to pull the post out. It's jammed in there! Any ideas? I guess I could just leave it on there...

Finally, how do you take the handlebars off? I feel dumb asking this one, but there is a spot on top where my allen wrench fits in but I can't turn it. Then on the bottom of the stem it looks like that piece should turn but I don't have a wrench wide enough to get around it. Guess I could try pliers? I don't have all the right tools yet but I'm trying. Thanks for your help and patience - I'm sure I'll have more for you later!