1) The document discusses various tips and best practices for using Composer, the PHP dependency manager. It covers how to install and configure Composer globally and for projects, managing dependencies and repositories, debugging issues, and advanced techniques like overriding dependencies.
2) The global Composer configuration allows setting default options and repositories to avoid repeating them in each project. Private repositories can be secured using SSH or SSL client certificates.
3) When dependencies need patching before being merged, forks can be required directly or used as replacements for the original packages. This allows using unmerged fixes until the changes are incorporated upstream.