1. Unfortunately there isn’t a built-in way to display a few pages at once (because pages don’t have categories).
The only way is to manually place them one after another..
2. The CSS Classes field is for inserting a customized class for the widget.
So you can insert for example: padding-widget
Then in Live CSS you can insert the following code:
.padding-widget{padding-right:20px;}
3. In the image you sent, you circles the author’s name and not the sharing buttons.
Anyway unfortunately there isn’t a way to display the buttons at the top of the post.
However regarding the place they’re displayed, you can set it in Theme Options > Sharing.
4. We’re checking this possibility.