How can you switch the j and k keys in vim?

You can do it, but this is a Bad Idea™! This is going to cause you grief down the road.

However, if you are dead set on doing this, put these two lines in ~/.vimrc:

:nnoremap j k
:nnoremap k j

As for left/right moving wrapping on lines:

:set whichwrap+=h,l

See :help 'whichwrap' (with the single-quotes), and note that the help says this is not recommended.