Usually, J and K move up and down file lines. But when you have wrapping on, you may want them to move up and down the displayed lines instead.
set wrap " if you haven't already set it
nmap j gj
nmap k gk
set clipboard=unnamed
This makes it possible to copy/paste between Vim and the system clipboard without specifying any special register.
yy yanks the current line into the system clipboard
p pastes the content of the system clipboard into Vim
This only works if your Vim installation has cli...