My tax return is pending. Today is deadline. Any problems and fees from IRS? "Federal return accepted 04/17/19" - this is AFTER deadline.

As long as you transmitted the return by the deadline, it's considered timely filed.  Should your return end up being rejected for any reason, you have until 4/20 to correct the issue and re-submit (or print if you can't correct the issue).  So it's ok if you don't hear back until after the deadline as long as your return has been transmitted and is pending.