Best tools for project. Please help!

Hi,

I'm forming an international design group. We design the patterns of
transistors which make our wireless world work. We are standardizing
on Redhat enterprise 4 for our O.S.

We need suggestions on several things:

1. An easy to use revision control system to keep the remote sites in
sync. Hopefully with a user interface similar to tortoise.

2. An easy to use bug tracking and/or project management tool.

3. Easy interoffice communications. Skype? Video phone? What works
on Linux?

Thanks a bunch for any responses.

.