I teach AP and college prep English classes, and I can speak only for my school, but the problem with passive voice is that when my students reach me (as juniors or seniors) they seem never to have heard of passive voice. Because true grammar teaching has been cut from so many elementary and middle school programs, when I try to correct passive voice or unnecessary verb tense shifts, my students often can't identify the verb; so it's difficult to correct the problem when they can't see the problem.
You will have to encourage your students yourself to write in first person. My students' previous teachers have told them "never" to use first person; so I spend time in my class teaching my students when first person is most effective, etc. You just need to specify that yourself. Most students will write to your specifications, but they must know what you want.
Finally, in regards to MLA format, that is standard for most high school English writing. Again, if you want them to use footnotes, APA style, etc., simply tell them that. The problem in my school is that my students write only for their English classes, and I'm not exaggerating. I have had numerous history, science, and math teachers tell me that they do not assign essays or include discussion questions on their tests because they don't feel like grading them. As a result, students learn to write solely for their English classes. The only exception that I can think of is that our AP U.S. History teacher teaches a great deal of writing, and the format that he teaches for his AP exam essays is different from mine, but I just tell my students how the exams differ and prepare them for being able to write to my specifications. You can do the same. It's hard work, but it's worth it if you truly want better results from your students.
It's easy to blame past teachers, etc., but the bottom line is that you need to set standards for your students, identify and model those standards for your students, and grade based on that. The students who are willing to work hard will meet your standards, and those who are apathetic would not have met any standard any way.
One last note, with so many students depending on TV and poorly written articles for their sources or reading Sparknotes, etc., instead of exemplary writing, our number of fluent writers will continue to decline.