A larger commercial building I would place in its own holding company - particularly if it were being purchased with partners.Even though you may not be able to see the entity and keep financing in-place, if you owned the properties outright at the time of sale, selling the shares in the holding company could very well be easier - and may have tax benefits - to selling the properties individually.In general, I am for using holding companies where the potential benefits outweigh the extra administration and accounting effort and cost.

The probate court may issue Letters of Administration prior to the expiration of the required 4-month advertising period, but only if the Court is convinced that there are sufficient assets, such as cash, to pay any potential creditor claims. 

Closing costs will be greater as you typically pay for the lenders legal, administrative, and closing costs.  

2) If I speak to an administrator and they agree to a cash deal can they enter into a contract or do they have to wait for the probate process to finish?

But you may also want to trot down to the Sac County recorders office (600 8th St) and using the public terminal key in the again decedent's name and/or subject property address to find current tax status.To get a hold of the executor/administrator you may want to pull the death certificate.

I imagine it can be quite lucrative depending on how much time and effort you put into it, especially in a large metropolitan area such as D.C.Do you know what databases these companies use to find rentals and renters?

For bankruptcy you have to research the federal court's data base, www.PACER.gov. 

Appraisals – Are these stored in a database somewhere?

do not get carried away, play conservative on your first deal, leave some room for error.3) Find a qualified and experienced contractor, do not settle for cheapest, you want experience here, because their is a significant administrative burden not only paperwork, proper formatting, but also financial constraint on the contractor as these sometimes have $0 prepayment to contractor.

When I search through the DC real property assessment database I discovered that alot of the vacant homeowners have $10,000+ in back taxes.