Some "problems" with new site (header/logo/post)

Hi everybody!
I just started using wp and I created my first site with Food theme by Mojo: panenus.com.

I am facing now some little problems:
– I don’t know how to insert sidebar JUST in the blog page (and posts)… as far as I can see it is possible only on the whole site or just on posts. How can I do that?
– in the pages ourservice/personal-chef and ourservice/catering, when you scroll down the logo disappear. Any idea?
– header is getting bigger when you scroll down… too bad!
– I would like to hide/cancel date+”comment” from the blog post header. Is it possible?
– I would like to insert share button in post pages without share count and statistics. Help?
Thanx a lot for any advice you could provide me nd for your patience:-)
Silvia