For your first question, how many times a day you use it depends on your actual oral situation. Flossing is like a toothbrush. If you haven't eaten some food that easily remains in your mouth, just clean it once or twice a day. On the contrary, there is nothing wrong with cleaning it several times, as long as there is time. Good quality dental floss, used many times a day, will not increase the gap between teeth and will not cause harm to the mouth.
I will answer your second and third questions together. In the dental floss industry, the first generation dental floss needs to be wrapped around fingers, the second generation dental floss is a disposable dental floss stick, and the third generation is a non-disposable dental floss stick. Comparing the advantages of the third generation and the first two generations, I won't introduce them in detail. You can ask me if you want to know.
The first generation of products has been eliminated for decades abroad, so I don't know much about it. A better brand of disposable dental floss stick is Chenqu style, whose dental floss stick is not produced by itself and the price is relatively expensive. Non-disposable dental floss stick, the best brand is Hua Shan dental floss stick, which is a national patent product with good quality. Specifically, you can also look at Baidu.
I hope my answer is helpful to you.