1. Theres only one teamspeak server, but there are multiple channels. Some channels are for members/donators and higher. Some pk trips or other events are for intro+ or members+. This will usually have a locked channel requiring you to be pulled in by a rank or requires a password.
We have the public cc "Sp33dy20", but also a private cc that requires you to be added. When you become a full member you can ask the higher ranks to add you to it.
2. This depends. If you help people out with resouces, help people when they're in trouble, and are nice to people in general, then they are more likely to come help you when you need it. There's not a big difference in treatment between intro's and members.