Writing Plays/Screenwriting/Screenplay registration and query letter.
I have just completed a screenplay. I am going to register it with the Screenwriter's Guild. Should that be sufficient for infringement protection, or should I also obtain a copyright? Also, how much personal information should be included in a query letter, and are they typically mailed or e-mailed?
Your first question regarding infringement (whatever that means in this context) seems to me that you are worried someone, or a prodco, is going to "steal your idea." Let us be very clear, one cannot copyright an idea. One may register or copyright a completed script. A screenplay contains ten thousand ideas. More significantly, a completed script contains characters, characterizations, scenes, and situations that make your script unique.
When you submit a screenplay for consideration by an agent or prodco, they go through enourmous hoops to ensure that your script is accounted for and who reads it because all of these companies have faced multiple lawsuits by writers over the years who have stated that they have "stolen their idea." In most cases, because of the accounting of the script, the writers are unsuccessful in their lawsuit. The truth of the matter is that if your screenplay is bought by a prodco, the script and all it contains, belongs to them. Also, most prodcos receive hundreds if not thousands of scripts every year. They are too busy to pull your script out of the slush pile and put their own name on it. Has that been done? Yes. But no reputable, Guild-represented agent or prodco would do it. Doing that is not worth the time and bad publicity.
If you have submitted a script to a prodco and some years later you see a movie similar to the script you presented, good luck with your lawsuit. Just ask the woman who originally wrote "E.T." and then sued Spielberg, et. al. She has never sold anything in Hollywood. Hollywood is a small world and people remember. The best advice here is to smile, grit your teeth, and move on to the next project.
Your second question deals with registration and copyrighting. Both actions perform similar, but different functions. WGA Registration establishes authorship of a specific version at a specific moment in time. The registered document is subpoenable should a lawsuit be necessary. It is adviseable that should you make significant (more than 30%) changes to the script that you re-register the script.
Copyrighting establishes that your name is associated with a particular title at a particular moment in time. The contents are copyrighted the moment you write the words down. However, a copyright is not subpoenable.
Your query letter should have enough information that the agent or prodco can contact you. If you are asking about a personal description on a query, just don't. You should have a short (three sentence) paragraph on your writing, production background. If you have no background then leave out the discussion. However, I would hope that you have attended screenwriting classes or contests. You can include statements that you studied under so and so or came in fourth in this or that screenwriting contest. Brevity always works.
Query letters are submitted in accordance with the directions of the agency or prodco. Go to WGA West and check out the list of agents. Some require only snail mail while some only want the query via the web. Do your research.