The "seller carried second mortgage" is just an ordinary second mortgage.

I'm not a tax professional, but I'd venture to guess that you'd pay ordinary income taxes (plus self-employment tax) on the income.

c) Exceptions The term ''personal holding company'' as defined in subsection (a) does not include - (1) a corporation exempt from tax under subchapter F (sec. 501 and following); (2) a bank as defined in section 581, or a domestic building and loan association within the meaning of section 7701(a)(19); (3) a life insurance company; (4) a surety company; (5) a foreign corporation, (6) a lending or finance company if - (A) 60 percent or more of its ordinary gross income (as defined in section 543(b)(1)) is derived directly from the active and regular conduct of a lending or finance business; (B) the personal holding company income for the taxable year (computed without regard to income described in subsection (d)(3) and income derived directly from the active and regular conduct of a lending or finance business, and computed by including as personal holding company income the entire amount of the gross income from rents, royalties, produced film rents, and compensation for use of corporate property by shareholders) is not more than 20 percent of the ordinary gross income; (C) the sum of the deductions which are directly allocable to the active and regular conduct of its lending or finance business equals or exceeds the sum of - (i) 15 percent of so much of the ordinary gross income derived therefrom as does not exceed $500,000, plus (ii) 5 percent of so much of the ordinary gross income derived therefrom as exceeds $500,000; and (D) the loans to a person who is a shareholder in such company during the taxable year by or for whom 10 percent or more in value of its outstanding stock is owned directly or indirectly (including, in the case of an individual, stock owned by members of his family as defined in section 544(a)(2)), outstanding at any time during such year do not exceed $5,000 in principal amount;"End quoteMy first followup question:It's my understanding that I need not be concerned about the impact of the Safe Act and licensing requirements if I'm using just my money to loan to others, and that I have a broker creating the loan documents.

Any extra money not contributed out of your earnings should find a good home in real estate that can ultimately reduce your tax on ordinary income.

Yes, for paying yourself but it doesn't usually make sense to do so since you will also pay self employment tax on that income on top of the ordinary income tax you will pay.

It's hard enough to build new investor relationships during ordinary times let alone in the middle of a global pandemic. 

Such entity in the ordinary course of its business must be engaged directly in real estate management or development activities.2) Expenses related to the real estate will be paid by the corporation.3) The real estate will not be used for personal use.4) There may be periods of time when the 50% test described in 1(a) above is not satisfied.

You stated you will only pay capital gains if held for 4-6 months, but the IRS sees it (flipping) as ordinary income with self employment taxes.

However, I'm interested to know if I develop and build a house on the lot then sell - how am I taxed - long-term or ordinary income?

When the down payment is 50k, this is a proportionally significant number.From a ROI perspective, I would like to bundle all these "startup costs" along with my down payment and closing costs into a lump sum (call it "acquisition cost") so that I can compute my cash on cash ROI.But this is in conflict with how the IRS will treat them -- as ordinary expenses.Besides not having a good picture of how my P&L is actually doing, I would like future lenders to see the higher (actual) profit, not a poor first year because of the startup costs.