I would keep couple things in mind though - the more multi-family you have, the more exposed you are to the issues as the number of doors and tenants multiplies.

Do they us a multiplier for various trads in different cities?

Does this book include all CSI costs for trades, either LS, SF, units & etc. for cities throughout the us with a multiplier?

Average it out and multiply that averaged price per square foot by the square footage of the subject property.

I multiply that by 1.5.

Note 2:  You'll find they will always do two things:  1) They will always start out by assigning 50% of the deal to them, as the finance partners; 2)  When they total up the percentages, the total will be somewhere north of 100% (I've seen as high as 300%)5 - After the percentages are assigned, and somehow the total is greater than 100%, verify that the ratios between the assigned percentages/role is accurate...then,6 - Divide 100 by the final percentage totals generated in step #4, and multiply each of the roles by that number. 

The monthly multiplier is .85% of the loan amount divided by 12 months to get you mortgage insurance payment.

This multiplied by a lot of properties over a lot of years is a whole lot of wealth.

For income they may use either the GRM (Gross Rent Multiplier) or Cap rates approach (the more popular method). 

) $10,000.00 Vancy (5% of Rental Income) $60.00 Repairs Damages) $50.00 Total Investment $38,750.00 Cap Ex(Replacement) $50.00 Cash Flow/Purchase Expenses 0.12 Property Management $120.00 Cash On Cash ROI 0.115395097 Total $827.37 Gross Rent Multiplier Purchase Price $100,000.00 Annual Gross Rent $4,471.56 Cap Rate Gross RM 2236.36% Gross Rental Income $4,471.56 Net Operating Income $511.17 Net Operating Income (NOI) 8.747696461 Gross Rental Income $14,400.00 Operating Expenses $6,134.04 NOI $8,265.96