Влад, зачем вы вводите человека в заблуждение и даёте советы, если сами не знаете? Так, как вы предлагаете - We are friends for 5 years - неправильно. Present Simple НИКОГДА не говорит о продолжительности действия. Правильно будет We have been friends for 5 years.
Kate is my best friend. We met at the university five years ago. Since then we have been friends for 5 years already. And I know that she WILL always help me if I need it without any questions or hesitations ( или she is always ready / willing to help me whenever I need her help). I AM glad that we ARE studyING together and WE can see each other every day. We have THE SAME OUTLOOK / point of view on many things and even if I don't agree with her, I know that I can express my opinion and she will try to understand me. We can speak about everything and laugh together. I hope our friendship will be very long, because if I DIDN'T HAVE such a good friend, Дальше не совсем понятно, что вы хотели сказать. "Такие же милые вещи в моей жижни не случились бы" ???Какие "такие же"? same nice things in my life would not have happened.
Лучше напишите ...my life would be different, because it would be deprived of many nice things I have now.
В последнем предложении или 2 или 4 (смешанный тип) условных, но никак не 3, ведь подруга у вас до сих пор есть.