The IRS is now allws a 90 day delay to pay your taxes, after Apr 15th. Does it mean that you can FILE until Jul 15th as well, or is it necessary to file before Apr 15th?

The details aren't known yet. It was just an announcement during a press conference today. What they seemed to say is that they are extending the time for paying, but not for filing. You still have to file by April 15. But more detailed rules will be issued in the near future.

The filing due date is still April 15. 2020. However, you can file an extension to file (form 4868) by April 15, 2020 which gives you an automatic 6-month extension.