This is great news and long overdue!   

It can be frustrating and lengthy based on the type of loan you go with. 

Officially converting a single family to Multi Unit is a lengthy process where you might end up with nothing.I would call zoning and get more information on the area. look at you lot size etc.... 

We've fired a few property managers for lengthy turns over repeated time frames. 

It turns out this was her childhood home which she had recently inherited and she just didn't want to deal with any sort of lengthy sales process on the open market.Am I competing with the zillows of the world?

Luxury Yacht (with decent expendable income) who owns a 3 year old SFH he rents out at market rate in a class B area to stable renters may make a different decision on what to do with monthly cash inflow than Just starting out on a shoestring and a prayer blue coller worker who owns a 70 year old class C that is overdue for a rehab.That is based on personal ability to meet costs when they come due and the probability that costs will come due.That being said, it's always intelligent to budget for CAPEX using real life numbers vs IRS or guesstimate numbers.You also need money for turns, which includes carrying costs when unoccupied and etc...As well as unexpected costs, such as roof damage, or early appliance failure--such as a refrigerator.Good Luck!

The seller is giving me a hard time about the length. I

Start an eviction process as soon as the tenant default, best case scenario you work out a deal and drop the case, worst case you move forward with the eviction and you didn't lose precious time trying to make things work (guessing you're in a C-D areas of Detroit, tenants are well aware of the process and like to play the watch to stay in the house for free as long as possible), navigating the courts since covid is a lengthy process so the sooner you start the better. 

Does anyone have or know where I can find a detailed/lengthy checklist for purchasing property from A to Z?

Few investors I feel hold sfh for any lengthy period of time of 10 yrs or longer.