The line-height property is for the height of a line (how ironic), usually this applies to text. The lines of the text will be spaced out vertically if you increase the line height (i. e. the lines become higher) while the
height property specifies the height of an
element (it’s a difference if you increase the height of the lines in a paragraph or the height of the paragraph itself).
For lists I would suggest using
height, perhaps together with some top and bottom padding for the list items (or perhaps scrap the fixed height and just apply some top and bottom padding). Line height can be useful as well but might become problematic with cross browser compatibility or if the text in the list items wraps.
If you use percents or pixels as values is completely your choice. If you want a liquid layout (adapting to the size of the viewport) or a layout that keeps the dimensions relative to the size of the viewport you should use relative units such as percent, em, or ex. If your layout is static you should use absolute units such as px (pixels), cm (centimeters), in (inch), mm (millimeters), pt (points), or pc (picas). These latter ones are probably more useful for print layouts so the
px unit would be the most appropriate for screen layouts. Also refer to
http://www.w3schools.com/css/css_units.asp Note that you can mix any of the units. For example you can specify your general page width in pixels and then specify widths of child elements in percents which relate to the width of the parent.
I don’t have the time to explain the other stuff right now as it’s a little more involved.
Before you post, read our: 
