I've obviously got a large starting capital that I'd like to multiply but I have no idea how much time it would take to (potentially) 2x, 5x, 10x my money. 

You should come up with a master percentage (decimal).6 - Now add up all the numbers that were assigned to each partner (Step #3),7 - and multiply that number by the number you got in Step #5.These are the percentages each partner should get, which are based on an agreed on relationship between the roles that each partner performs.I've NEVER, in all the partnerships I've set up over many long years of using this method, have I EVER had a problem with the results. 

If you had owned lived in it for 6 months in the past five years (and qualified for the reduced exclusion) you would take the $500K exclusion and multiply it by 6 months / 24 months or 25%.  

As a 5 unit commercial unit, if I multiply the income by the Gross Rent Multiplier (~8) then there is a ton of upfront equity.

As in, are you dividing all your utilities,lawn care, etc on a daily rate and multiplying that by the daily vacant rate? 

If you have a 1-2% rise in interest and multiply that increase in payment over 30 years, that's the cost of sitting and waiting.

Multiply by your nightly rates.

Which data points should I be multiplying in order to find closing costs, property taxes, repair/maintenance, insurance, future sales prices of the home, and capital expenditures?

For me, the income from the STR is a huge multiplier over what I get from the LTRs so for me it is worth the extra work involved.  

OR2) Average Price per sq. foot of similar size houses in the 0.3 miles radius (multiplied then by the actual square footage of the assessed property ?