How long does it take to write a screenplay?

I am currently going to Film School and in my 2nd quarter. I have about 2 years more till graduation. The next class I would take would probably be a screenwriting class. I had a class prior to this one that helps generate ideas for film,books and novels...

Lets say you are failing most of your AP classes, but there's a scholarship that offers you a free ride into college if you write the best screenplay, and you get 1st place. Do they let you take all of the classes at their school? (This is research btw...

I came across a screenplay called "the room at the Inn" on this screenwriting website I go to. The writer put "inspired by Steven King's 1408" but when I was reading the script, I realized that the writer basically copied the movie...

Of course, I'm not referring to a non-linear narrative, I'm referring to writing individual scenes rather than writing the screenplay from the beginning. Would this leave me liable to inconsistencies and plot holes? Has anyone else used this method to...

I think it'd be fun to write a screenplay, and I have a couple of ideas that I'd like to develop. I have professional writing experience, but it's been dry, academic stuff -- my creative writing skills are not too polished. What kind of training is required...