This sounds like a very interesting project. I think you’re right to say that students will develop their vocabulary and other skills. After all, reading is one element that contributes to learning our first language.
First of all think about the level of the texts you use. I know you mentioned authentic material; so try to choose something that is slightly above the students’ level. This will expose them to challenging material that they can understand when they make an effort.
You could produce a standard worksheet (or dictate the questions to students) that is used with any reading material. You can include questions that encourage prediction: e.g. what do you think the text will be about? What do you think will happen? You can also get students thinking about the topic before they read; e.g. for a text about travelling by train, students can think about journeys they’ve made. Questions about prediction and previous knowledge are best if they are considered before reading.
I think it’s best if you don’t give students a task while they are reading. By doing this, students can just read and enjoy. They will still learn a lot without answering questions or doing a task.
After reading, students can relate the text to their own life; have they ever done something similar, do they know somebody who has? How would they behave in that situation?
Think carefully about whether you want students to answer the pre-reading and post-reading questions in writing. Writing things down will be more time-consuming and might make the reading project feel like a chore. They can benefit greatly from just thinking about the questions.
After reading the text, students could be asked to choose 5 words they have learnt and to note them down somewhere. They could also write one sentence about why they liked or didn’t like the text. These sentences could be made available to other students who are trying to decide what to read next.
I hope you and your students will enjoy these activities.