The help system is designed to evolve over time; running update-help downloads the latest content.
When searching for help on items, you can simply type help commandname to get information about a command.
If you're not sure what you're looking for, but have a rough idea, you can search on partial command names, or even specify specific verbs to get a list of commands potentially of interest; e.g. help -verb write.
The information in help gives a good overview of the commands you're looking at, along with code examples, so you can see real-world usage without resorting to the web.
When calling a method with multiple parameters, rather than passing one variable per parameter you're able to "splat" one variable to the method, with the parameters taking their values from its properties.
Though Windows Powershell only works on Windows, the open source implementation Pash (http://pash.sourceforge.net/) allows the same language to be run on other OSes.