Memorizing music gives you that much more freedom to make music. Not bound by what you see but what you want to hear. When I worked on a piece for a recital or solo concert I would start out by playing it over and over and it didn't take long for me to memorize it regardless of how hard it is. But then you must start to feel the music and understand the phrasing and why the marked dynamics are marked that way. You can go past that and express the piece with your own phrasing, tempo's and fluctuation.
Playing a piece that you actually feel is so much more enjoyable than purely reading it.

I'll try to answer all those questions.

We have new repertoire every week so we don't have the music memorized.

I didn't say that we couldn't play musically with the music just that you are free of that reading task and can play more musically without it. So the musician is responsible to play musically even with the music.

The conductor is actually responsible for the artistic interpretation Oliver though usually they get credit if everything goes well. When things go badly the orchestra is blamed. LOL

The REAL GOOD musician doesn't glue his eyes to the music, rather looks around and throws an eye at his colleagues and conductor periodically while performing. Traditionally the violinist should look to their right and forward towards the leader. If you are a second violinist you look to your right and try to see the section leaders bow as much as possible otherwise the guy in front or in front to your right. If the second violin section is wrong it's the section leaders fault. You don't try to lead from the back even if the leader is wrong or there can be chaos.

The section leaders should look towards the concert-master. All sections that have the same part should listen to each other and play together.

The concert master is also responsible for the orchestra playing together as well as the conductor. He is allowed to speak to the orchestra and give advise, criticism, and suggestions. He can also advise the conductor but some conductors don't stand for it.

Musicians are able to see the conductors beat while staring at the music in the corner of their eyes though I prefer to have eye contact as much as possible when I play. Even if I am reading a piece I look forward quite a few measures and can easily continue playing for a while without looking at the music. Kind of when you speed read a book or something.

Conductor is the guy with the stick NV.

The concertmaster is the no 1 leader of the first violins and via tradition and placement is appointed the leader of the orchestra as well. He also comes in right before the conductor, takes a bow in front of the orchestra, and tunes the orchestra. Most violin solos are played by him.

PS. When I say "him, he" I mean "him, he or her, she" It's just easier. Sorry.