Well, since I strongly believe that life is in the details of everything, I must say, that you have yet to be exposed to the concept of paying attention to these at times very small but all important details. In your writing you wrote "whats" and that is not correct as contractions require an apostrophe: what is is contracted as "what's." I get the feeling you know of this rule but since other teens using the teen texting code slang shorthand ling version of English do this without consequences, then, it must be OK. Well, it is not. Neither is not capitalizing proper names such as Ford and Fiesta. Same convenience and same major error. Same with number numbers. You wrote "a 3 year old" which is not correct. It is "three years old." You continue with run-on sentences which are two or more sentences all in one. After the "Ford Fiesta" starts a new sentence. Then we come to the automotive question. Again, the details are missing since, apparently, someone purchased this vehicle for you at what ever age you are but you were not instructed that the owner's manual, a booklet that was placed in the glove box or arrived with the vehicle from the factory, has most of the applicable information that an operator must know or be familiar with as to this specific vehicle. It is in this booklet that the information you wish to know is contained. Again, details that escapes a huge amount of the population as reading about the car they own and operate is rather tedious and boring compare to just driving. I would bet that your parents have cars and they never get to read the books in their cars. Well, they should. You have a question as to the fuel system? Read it in the booklet. You wish to know as to operation of the wind screen water wipers? Read it in the booklet. You wish to know as to precautions to take in slippery weather? Read it in the booklet. I shall warn you as to your original question. Maximum distance? The foolishness of driving in a low level state of fuel quantity is attempted by millions of drivers each year. For the most part it ends in failure. The American Automobile Association, AAA, reports that the number one reason for road assistance provided to their members happens to be running out of fuel. It is a sane and reasonable and logical decision to fuel up when the fuel states indicates 1/4 of a tank. It is also a foolish notion to start the vehicle and not to pay attention to the indicators, lights, etc. on the dashboard. Some drive with parking brake on and others with an inoperative alternator. What is the indicator in this car that shows an inoperative alternator? Read the booklet. Read it. As to your writing deficiencies, well, if you read any published books, textbooks, news, etc. and you pay attention then your writing shall improve. But for the most part, the texting thing, it is all 100% wrong.
No matter how far it goes, you are running the risk of burning up your fuel pump, that's the reason for the low fuel light. To help keep you from damaging the fuel pump, it's NOT there for your convenience.
No "set answer" for that. Each car would be slightly different.
If you really want to know, carry a spare gas can in the trunk and once the light comes, drive the car until it quits. Then pull to the side of the road and pour in the spare gas.
Not good to run 'em out of gas though. I never run low enough for the warning light to come on.