How does merging work?
See merge
What are some best practices for distributed development with Mercurial?
See WorkingPractices
How do I import from a repository created in a different SCM?
See ConvertingRepositories for various tips.
What about Windows support?
See WindowsInstall for getting started using Windows.
Is there a GUI front-end?
See OtherTools for information on graphical merge tools and other front-ends.