You can only go so far before you need to add ventilation pipes/devices.I once had a local flipper hand me a remodeling diagram that would necessitate chopping holes for a 3-inch toilet line through four 80-year-old 2x6 joists to the nearest stack.

20 to 30 days.15 IF You supply everything upfront: full application 1003, mortgage bill last month showing paid as agreed, all insurance bills not the policies, your bank statements past 2 months for reserves, lease agreement for subject, comparables for subject, purchase contract if purchase or just fire insurance and any HOA documents (Certification/Master policy/HO6), you have no loan modifications on credit or in closet, pay for appraisal fast with credit card and they get inside the next day, no funky clouds on title, no soon to be partners or LLC not documented, proof of deposit check or rent check at closing.

The vast majority of RE repairs and modifications are not difficult. 

Honestly, I was quite surprised the Seller swiftly accepted my offer without any modification.

Any modifications made and filing of modifications made to the note and deed of trust.

Are there any modifications to the written lease?

I have to do a review of the plans after I get them, I just don't want to spend $3,000 only to get a sub-par plan that I have to do a large amount of modifications to (other than site specific items), in order for it to actually be something that can be built.

Small modifications not needing structural improvements?

I would definitely investigate the way the property is piped & wired now to see the extent of modification required to get each unit independent utilities, it may not be bad at all or may be terrible.If it's terrible I would see if the local utilities provider has something equivalent to a "RUBS program" (ratio utilities billing system) which bills tenants directly based on usage in proportion to the square footage of each unit. 

I believe any modifications/accomodations to the property to keep the neighbors/neighborhood safe are to be borne by the tenant.