You should choose No when it asked you about dividend income, it is different type of income and it only can be paid by financial institution. 

You correctly selected select "Other self-employed income, includes 1099-K, cash, and checks". Since you didn't receive tax form regarding the income, it is considered Cash income. You can continue through the interview to enter your business information, income and expenses.

I have a 1099-DIV that I do need to file for an investment unrelated to my self-employement but I haven't received the paperwork yet. After I file the unrelated 1099, will it still prompt me to file a schedule C for my self-employment?

Thank you for your help!

You can have your income from different sources, and you have to report all of them. Your dividend income doesn't affect reporting of your self-employment income.

It is better to wait until you have all your tax forms to file your tax return in order to avoid complications and amending your tax return.