I don't think that there is a single "best" solution to this. What works for one team might not work for yours.
Video conferencing is a big plus. It really does help team-building if you can see the other members of the team. You don't have to do this everyday, but having a team video call as one of your weekly meetings at least once a month will help.
Having a group telephone call as your weekly meeting is probably a must. I'm currently working on a project where our partner team is in the US. Our weekly meeting happens in the afternoon UK time and first thing in the morning US time. You need to find a time that's mutually convenient - or at least not too inconvenient for all participants.
With regard to language - pick one that everyone knows and use that. It may even turn out not to be the first language of anyone in the meeting. I was at an international meeting once where the official language was English, but a Spaniard and a German conducted a side discussion in French because that was the language they could understand each other best in.
As for cultural sensitivities - education is necessary as is environment where everyone knows is OK both to raise an issue and (as long as it's not malicious) make mistakes without fear of too much backlash. If someone says something out of turn, say so straight away and move on.
If you encourage team members to talk on Skype (or other instant messaging system) outside the meetings then people will get to know each other and this should become less of a problem.