Post X of Y in single.php / sidebar.php

Is there a way of putting “Post X of Y” into my sidebar? I think I can only show it when it is a single blog post (something like checking if the content is_single) but I want to be able to see which post I am viewing. Googling “wordpress post x of y” for the last 20 minutes has given me a lot about category x in page y or something similar, so I thought to ask here.

Limit widget to certain sidebar?

I have multiple “sidebars”, but not all of them are the same size. Not all widgets fit in all sidebars (for example, I have a “footer sidebar” where the client can place custom widgets, but they are wide, and don’t fit at all in the “real” sidebar). I want to give an indication when a widget is placed in a sidebar where it would not belong (change the header text color, for example). What would be the best way to do this?

Call sidebar from a template

I need to call a sidebar into my header. I’ve switched to the new twenty twelve theme and created my own child theme. With this new theme I decided to keep things organised and together, so I put my widgets functions, stylesheet and two new sidebar templates (one for header and one for footer widgets) in one folder called pgwidgets.