For '1' you need to clone the existing template for the 'login' layout (http://docs.moodle.org/dev/Themes_overview#The_different_layouts_as_of_21st_April_2013) and change that file to remove the main bar.
To be honest a complete 'step by step' guide would take me quite a while to produce and I'm sorry but I don't have the time.
You can learn about theme development in general by reading this: http://docs.moodle.org/dev/Creating_a_theme.