How do I manage the fears of settling into a new team?

• Breathe in and breathe out. A new beginning should not start with worry. It should start with aspirations. 
• Get to know your teammates. Schedule coffees with them or take them out for lunch.
• Remember that you are amongst people who have known each other for quite some time. There will be moments when you feel excluded. Usually it is nothing personal but just the fact that your team members are more familiar with each other.
• Find a mentor.
• Ask for a buddy to help you settle in.
• Focus on adding value to the team. Show them what you bring to the table.
• Start an interest group. It could be work related or maybe something to do outside work.
• Give it time. Friendships and trust are not built overnight.

What do I do if someone steals my idea and pitches it as their own?

• Might be best to vent out emotions in private first. Kickboxing? Darts?
• The best thing to do is to raise the issue in private with your colleagues at the first instance. Avoid accusatory tone and ask questions by presenting facts. This makes your point, but also gives your colleague the benefit of doubt. Sometimes, people are just careless.
• If the problem persists, then (i) avoid disclosing your ideas to this person in future; and (ii) report to your manager.
• There is no point seeking revenge. Best to come up with a better idea. That is the best way to make peace with the situation.