Show separately for 2017 and the 3 preceding years: gross sales, cost of goods sold, gross profit, percentage of gross profit to gross sales, amounts collected, and gross profit on amounts collected.It seems, after reading this, that your solution would be the correct one - enter the gross profit for each year on Line 1 of Schedule C with a separate statement attached to the return describing the installment sale and how you arrived at the gross profit. 

I know there are a lot of different marketing strategies out there for wholesaling but can ya'll share what has been the most effective/ has led to the highest percentage of lead generation for you?

I guess my intentions for partnering with him will be considered syndicating, what should I ask for as far as percentages and what should I offer such as time or managing the property? 

The previous years are there for comparison.Number of liens sold to investors:2018 - 1,739 (1,376 bought by investors - 363 Struck to County as no bidders)2017 - 2,141 (1,902 bought by investors - 239 Struck to County as no bidders)2016 - 1,880 (1,600 bought by investors - 280 Struck to County as no bidders)2015 - 2,039 (1,808 bought by investors - because 231 struck to county as no bidders)2014 - 2,5752013 - 2,382Total dollar of liens sold:2018 - $1,776,766.27 ($1,594,714.45 bought by investors and $182,051.82 not sold) 2017 - $2,175,069.34 ($1,890,259.85 bought by investors and $284,809.49 not sold)2016 - $1,874,010.88 ( $1,694,277.89 bought by investors and $179,732.99 not sold)2015 - $2,678,533.35 ($2,336,551.03 bought by investors - $341,982.32 not sold)2014 - $3,015,871.872013 - $3,435,014.32Average rate of return overall:2018 – 6.53% (5.45% by investors when subtracting out struck to county liens which all get 16%)2017 – 7.26% (5.94% by investors when subtracting out struck to county liens which all get 16%)2016 - 6.28% (5.25% by investors when subtracting out struck to county liens which all get 16%)2015 - 6.75% (5.40% by investors when subtracting out struck to county liens which all get 16%)2014 - 5.86%2013 - 6.55%Number of Investors who won liens:2018 - 872017 - 972016 - 742015 - 892014 - 1162013 - 201Total Number of bids for all liens:2018 - 11,8982017 – 10,5502016 - 8,8232015 - 10,5252014 - 18,8122013 - 99,073,789You bid down the interest rate in 1% increments from 16% down to 0%.Percentage with the most number of bids overall:2018 – 5% had 1,783 bids2017 – 5% had 1,315 bids2016 - 4% had 2,680 bids2015 - 6% had 2,391 bids2014 - 7% had 3,542 bids2013 - 4% had 36,251,623 bidsMost bids per lien/parcel:2018 – 1 lien had 28 bids2017 – 3 liens had 23 bids2016 - 3 liens had 20 bids2015 - 7 liens had 24 bids2014 - One lien had 41 bids2013 - One lien had 470,295 bidsCreated a Pivot table where I grouped the liens by "Property Use Description".

Just divide your cash invested by the Net operating income and it gives you the percentage of cash on cash.

How much of a down payment is typically expected when the owner finances, in terms of percentage?

This should be beneficial only in determining your price-per-door relative to, or as a percentage of, comps, and not when determining your offer price.Instead, as @Patrice Penda stated, your offering price should not be determined by nearby properties, but rather the property actuals.

Issues that I’m currently running into are significantly higher rates (I realize they have gone up nationwide) and the LTV percentage that the bank is willing to use.

Even with competitive lending terms and rates this process will understandably create a significant reduction in cash flow and increase the loan to value percentage for the current portfolio of properties.

Now how that's divvied up, I don't know - they may want to 'assign' a property per brother and come up with some for of equity/asset trust 'equalization' so we each get a third of all their assets but hold different percentages of any particular asset.