
So my first Thought will be on confidentiality.
What is it?
Confidentiality is a an ethical concept. Legally, I'm required to present the parameters of confidentiality to a client prior to the onset of therapy. They need to know what's not covered before they agree to participate. Most everything (I'll qualify this more later) disclosed between a therapist and client is confidential; that is, I can't just go telling anyone what a client told me in session. It's considered privileged information, but this is actually a legal term I'm not going into on this post.
I can't share anything from our sessions unless I have a client's express written permission (or in the case of multiple clients--like a husband and wife--a signature from all involved parties). Verbal consent can only me used in emergencies, and all therapists would have a form for this express purpose, usually called a waiver.
Who/what does it cover?
Confidentiality is very extensive. If you tell me you have $1000 in outstanding parking tickets, I can't pick up a phone and call the local police station. If you bring in photo albums or journals to share, the information in them is all covered. If you tell me you committed murder (or some other crime), I can't call the cops to come get your murdering self.
Many times therapy is between more than just one person and the therapist. In that case, everyone is covered. For example, a husband needs proof that he attended anger management sessions for his job, but his wife attended some sessions with him and some of what he's requesting came out during one of those sessions. I'd have to get the wife's consent, as well.

Many times, other professionals are consulted on a case. Say, a client needs to have a physical check-up to rule out some medical reason for depression. The results of the exam are given to the therapist, and this is kept confidential.
What's not covered?
It is not a blanket cover indicating that whatever goes on in the session will be kept between the therapist and the client no matter what. Basically, there are three scenarios where confidentiality would not be upheld in (i.e., legally, I'm mandated to report to authorities if the following scenarios crop up in therapy):
1) Client poses a danger to himself. Suicidal clients have to be treated with extreme caution and care. The therapist, acting on behalf of the best interests of the client (in the therapist's expert opinion), would reveal certain information to a crisis response team or a psychiatric hospital or possibly the police in order to ensure a client doesn't harm him or herself. A suicidal evaluation would be done by the therapist to discover if the client has a plan to kill themselves and how strong their motivation is (i.e., how lethal is the plan and how accessible would someone be to help?).
2) Client poses a danger to someone else. Homicidal tendencies can come out in therapy. I'm not necessarily talking about a a scorned woman's comment through her tears, "I'll kill the witch if I see her!" However, even this type statement should be looked into further by a discerning therapist. If the therapist has reason to believe truth to a statement, then he or she would have to further analyze the means, motivation and method the homicidal patient might have to see how big the threat is. Then information is disclosed to authorities accordingly.
3) Client reveals a know

Even if the client reports hearsay, the therapist has to report. "My neighbor told me his kid's best friend was abused. I guess you can never be too careful." All the therapist needs is a "reasonable suspicion" to disclose information. In the above scenario, I'd have to call the authorities and report what information I could gather (name of the child abused, where it happened, etc).
What about minors?
Disclaimer: everything I'm about to write pertains to California laws concerning minors. It does vary from state-to-state.
A minor is entitled to a confidential relationship even if they aren't the paying party. It behooves the therapist to form a contract with the payer (i.e., parent) at the beginning of treatment to determine what will and will not be disclosed to the payer. Parents are legally entitled to any and all information based on the minor's best interests, but LMFTs are obligated to maintain the minor's confidentiality. (I mean, come on. How many teens are going to open up to a therapist if they knew the therapist was parroting everything back to their parents? Hardly makes for a bonding, therapeutic relationship.)
So the therapist has to balance their ethical duty toward the client (minor) with the legal right of the parent. The best way to do this is for the therapist to first try to talk to the minor first, and urge them to consider sharing pertinent information with their parents. If that doesn't fly, then the therapist can ask permission from the minor to share the information with the parents with or without the minor in the room. If that doesn't fly, then a summary would honor the parents' rights to access the records while protecting the best interest of the client. This way, if a father requested info, you could leave out, for example, the fact that your client said he hated his father when you give a summary.
Well, that sums up confidentiality. Hopefully it wasn't too boring, but this kind of information could be very pertinent at some point to a WIP! :)
If you have any other questions about more specific confidentiality things, lemme know in the comments section and I'll do my best to ferret out an answer for you.