Excessive pressure on the vocal chords is caused mainly by belting. Belting can be a desire for high volume, or because it takes more air to reach higher notes.
Having problem breathing is very important for singers. Breaths should come deep from the diaphragm. The air should be unrestricted as it comes up.
Another good tip to help breath come out properly, allowing better tone control, is to start the phrase at the end of the inhale. A space in between sound and the inhale can cause very minute shocks on the vocal chords, making the air more restricted, placing more pressure on the folds.
Hitting high notes doesn't mean you have to scream. Again, it's all about breath control. Singers, especially amateurs, tend to start shouting and using excessive pressure to hit those notes. All it really takes is a deep breath and control from your diaphragm. Hitting those notes, even increasing volume, doesn't have to be excessive. This will in time cause the bowing you don't want to have.
As mentioned, dairy products are usually avoided for serious singers. However, every body processes food differently than the next. It's a good idea to figure out how your body handles dairy. If you have milk and find your throat being a bit congested, it's advised to be lenient on the intake. Drink a glass of water after some ice cream. Dairy products can cause mucus build up. This won't damage your vocal chords on its own. It's the sound and tone you will hear that will cause you to over sing or sing a bit off.
Smoking is also a biased lifestyle. There are singers who are old and have been smoking a long time who sing amazing. Others you can tell they are smokers. Again, if you smoke you will only know how your body reacts. You can get with your doctor to analyze results. Over time you can see if any significant damage has been done. Basically, smoking is unhealthy under any circumstance.
Vocal workouts are imperative. Every day, running through scales will help keep your vocal chord's flexibility.
Basically, bowed vocal chords come from excessive pressure. Excessive pressure comes from poor habits that affect singing. Your simple daily routine can greatly make a difference