- If you need to email someone, don't forget to be pleasant (it actually can make a huge difference - saying something as simple as "Hi Jim, I wanted to let you know that there may be a problem with your spec. I believe it should be
- If you're replaying to an email/communication with lots of people, be specific in whom you respond to (i.e. the "Hi Jim" comment above). It makes you come across as much less "curt" or blunt.
- Ask the more senior programmers for advice there. They will know the 'political landscape' too.
As for keeping the team informed, ASK THEM WHAT THEY WANT
It may be as simple as telling them "I've met milestone 20131112, I'm moving on to the next task unless someone needs me to work on something else."