Hi There,
It seems like you have changed some codes from the template files.
So please make sure you have the right blocks in proper places as in the default theme file. As per our defualt template you can take help of documentation to configure specific blocks.
There is no option to remove the menu but you can do by hiding it from css.
You can create galleries from the media uploader in backend and place the gallery code in the specified block as in demo/documentation.It does not require anything extra.
Thanks!