It's just what it sounds like: if you paste text -- not including an end-of-line character, BTW -- into the command window, Rhino automatically submits the command. This makes it difficult to calculate values (e.g., partial point coordinates) in some other program, then copy them into Rhino's command window. Instead, you have to create the complete command in, say, notepad, then copy that to Rhino.
Yep, this is true. It may help, in some cases at least, to use command line math using the =(math) format- for instance
Note the first time you do this in a session, there is a lag while Python loads up....