You don’t have to type the tree name (www-apps in the example) nor the version when using emerge. You only type the version if you need to install an older version. (which is not possible in debian/ubuntu without removing repos manually)

Binary packages are available, if one knows what they are doing and can install just as fast as in debian/ubuntu. There is also a prototype package manager called Equo in Sabayon which is binary based and is similar to apt-get in features and speed.

Portato is quite easy to use, and so is Porthole. If you can’t figure out how to use them, you should stick with a beginner distro like Ubuntu or PCLinuxOS.

BTW to check package size you just type “equery s ” Equery is just one of the many useful command line tools for Portage.