I can recommend a bunch but it depends on what type of loan you are looking for.

Generally, it is better to try to come to an accommodation with the senior lien holder before purchasing at auction, but that can sometimes be a challenge depending on the nature of the loan and the identity of the lien holder.

Never depend on the seller's vacancy numbers, instead figure out the market vacancy rate and round up.Taxes are always understated.

It would depend on what's in your new lease.

Vacancy can be 0-25% depending on turn over and what month they move out.Maintenance depends a bit on age of home but I would use about 0.1% to 0.2% per monthCap Ex depends on traditional (.5% a month) or private money (1%)Sales Expenses:  6-8% for closing and realtor plus about 2-4% for holding costs

I think it depends more on what you'd do with that $40k than the money itself. 

Spencer Hsu I offer full real estate services in Indianapolis and believe I can assist you with your first duplex depending what your price point is.

I do agree that starting with lower valued properties lowers the barrier to entry and lowers the potential loss amounts in some fashion.

It depends on where your location is, in downtown LA, you can't build anything under 150/sf.

Close the deal(through the title company or an attorney by way of double close or assigning the contract- it depends on the laws in your area) and collect your check.