All of these tenses are correct when discussing rumors or gossip. The reason "I hear" works is because what you're really saying is that people are talking about this now, and so you hear it regularly and from different sources. In fact, you can even use the present continuous: "I'm hearing rumors about that company."

There is no need to be confused, Bibinur. All of those sentences are fine. What isn't good, however, is your lack of capital letters! Remember that you need to start every sentence with a capital letter, and that the pronoun 'I' is always a capital letter. Capitals aren't optional - you have to use them if you want to write clear and correct English.

Here is a very simple explanation of the English present tense with several good example sentences: http://www.grammar.cl/Present/Simple.htm