How long IF at week? I’m confused, to many different opinions

Hello I’m new on IF diet and I have some question, 1) how many days I have to IF? I read in an article that you should do it for 5 days at week and the other 2 eat normally, in another article that you can do it just for 2 weeks at month and than stop, I’m on a weight loss journey and I wanted to try. 2) I’m following a caloric deficit diet, but in my diet i stick little treats like : yogurt, a biscuit or a little portion of dessert, can i eat those things in a IF diet?? I read that sugar is forbidden, I don’t eat a lot of them like just once at week, but I like to put a little of sugar in my coffe, can I?? 3) there are in general forbidden food?? Things to avoid because don’t help the fasting?Thank you and sorry for grammatical errors, English is not my first language via /r/intermittentfasting https://ift.tt/2rathwg https://ift.tt/eA8V8J