git submodule update "checkout" update mode

Hi,

In 2.0.0 release notes (00eda23),
Newly cloned submodule repositories by "git submodule update",
   when the "checkout" update mode is used, will be on a local
   branch instead of on a detached HEAD, just like submodules added
   with "git submodule add".

It is not clear.
1. Is "checkout" update mode the default? (when without any command
line options)
2. Does "merge" update mode checkouts a local branch instead of on a
detached HEAD?