Login and registration problems

1 .- How I can put facebook login button anywhere on the site?
No wighet

2 .- Remove permissions necessary. Leave the basics I need

3 .- When you register using the form plugin. Go to this link Thank you for Registering. Proceed to main site. But not end the process of registering a new blog

4 .- When you login or register is redirected to the index. As I can put that link to wp-admin?

Thank you

Sorry my English is very bad