Sorry about 2). I'll let the w3c answer on 1):
Cascading Style Sheets, level 2 revision 1, Section 5.6
http://www.w3.org/TR/CSS21/selector.html#child-selectorsA child selector matches when an element is the child of some element. A child selector is made up of two or more selectors separated by ">".
Example(s):
The following rule sets the style of all P elements that are children of BODY:
body > P { line-height: 1.3 }
Example(s):
The following example combines descendant selectors and child selectors:
div ol>li p
It matches a P element that is a descendant of an LI; the LI element must be the child of an OL element; the OL element must be a descendant of a DIV. Notice that the optional whitespace around the ">" combinator has been left out.