First of all, a lot of the problems people encounter in CSS are simply misunderstandings because of strange browser implementations. Nothing will help you more than actually reading the background materials and understanding what each piece of terminology really means. Once you grasp the overall concepts you will find that browser compatibility isn't just a lofty ideal.

Oh and to center you just put text-align:center on the container and margin:0 auto;text-align:left on the element you wish to center. It's really not that tough ;)

Having said all that, how in the world do you explain the lack of proper clearing? I think, at this point, it is obvious to anyone that has ever implemented a holly hack(usually not a good idea, btw) or a fixer class that an element should be able to clear the floating of elements within itself. This lack of internal clearing is one of the most obviously missing pieces from the CSS system. And so my question is, how could smart people forget to put something so necessary into the framework?(I hope there is a cool story involving some sort of conspiracy.)