With verbs like "pick up" sometimes you can separate it by putting the object in the middle "pick THE PENCIL up" but in this case it sounds much better to say "pick up THE PENCIL." "Collect" wouldn't be the same as picking it up off of your desk or the floor, for example. It would be more like going around an office or room and taking the pencils from everyone until you have a bunch of pencils. To clarify the difference between the two: a teacher in a classroom may say, "I will come around and collect your papers" after giving a test. Then if she drops one on the floor while collecting them, she will pick it up off the ground.

I agree with Jan except I don't think you need "aloud." If you're reading a book to someone, it's implied that it's out loud.

I would use the subjunctive for both of these if you're giving directions to someone because the idea is that you don't know when they will arrive. "Cuando/Una vez que llegues a la estacion (cuando sea, yo no se cuando vas a llegar), gira a la derecha. If you were to keep it in the indicative, it would imply that it's a habitual action. For example: "Todos los días cuando/una vez que llego a la estacion, siempre giro a la derecha."

I would say "These days learning English is a must. If you don't know English, you miss out on many things and have a lot fewer opportunities." You don't have to change the order of the first sentence, but I think it sounds slightly better. You wouldn't say "lose" for opportunities. It's a missed opportunity. However, to avoid repetition, I would rephrase it this way. Hope it's helpful.