My friend formed a LLC and aided to do real estate investment. The IRS assigned the form 1065 in form SS-4 to the LLC. However, my friend is the single member of the LLC since he formed this LLC, and he didn't file the form 8832. In 2020, the LLC had no business income generated, but received 6K dividend income, 1K interest income, and 30K short term capital gain from stock trading. He has couple questions about 2020 income tax reporting.

1. How should he report the dividend, interest, and capital gain? Should he just report to schedule B and schedule D along with form 1040?

2. The LLC had no business income generated, but my friend had some business expense, can he file schedule C about this net business loss?

3. What the due day of the Form 568? How can he apply extension?

4. Is the $800 LLC fee due on 4/15/2021?