Yes this is fine. It is physically similar to intermittent fasting.
No you will not dehydrate because there are ways to stay hydrated (see below).
People have done this for hundreds of years, and all over the world today with even less resources than we have.
Yes there are exceptions, especially for those who are ill, pregnant, nursing, and more.
For more persuasion on its practicality, see these insights from professional athletes partaking in Ramadan during the season: Hakeem Olajuwon, Ibtihaj Muhammad, and Hamza Abdullah.
And because this is another very popular question: yes, if you are so close to dehydration and fainting and near death, it is acceptable to break the fast in order to maintain your health.
Tips for First Timers:
Observe your consumption prior to the day(s) you want to fast. Be mindful of how you are setting your stomach up to be hungry later.
Contrary to popular belief, it is not recommended to overeat during the nighttime hours. Portion control allows for ease during Ramadan.
Eat foods high in protein during Suhoor (early morning meal), ie: a protein shake, eggs, oatmeal, avocado, yogurt, etc. Drink plenty of water during this time period. Coffee is not recommended as it is a diuretic, but can be consumed during this time period.
Once you have made it to Iftar (congratulations!), introduce your body back to food and water slowly. Do not try to eat a days worth of food in the first ten minutes, no matter how adamantly your mind instructs you to. Most observers break their fast with two dates and water (in the way of the Prophet (pbuh)) , make the Maghrib prayer, then resume eating. An alternative is to eat a small meal upon sunset, wait a couple of hours, then eat another meal. This time period is ideal for fitting in more nutrients from vegetables, meat and grains.
Be prepared to adjust your sleep and nap schedule in relation to your fasting, especially if it is your first time.