I've found that larger (80-units or more) apartment deals that come from wholesalers are usually a waste of time - mainly because the financials (like T12s, Rent Rolls, etc) are incomplete. 

I've narrowed my strategy down to two routes: send mailers out to my county tax delinquent list, or select a neighborhood that is mainly vacant but is fully platted and has some new construction popping up (there is a specific neighborhood I have in mind). 

Before going to an attorney I would ask the main partner if they already have an operating agreement structured. 

I suppose I should've mentioned my "why" factor.

@Alexander Felice I agree there are more factors to consider.

My questions are 1) Is it better to get a "separate" address or should I ask for Unit A (main house) and Unit B (ADU)?

However, my main source of income is buying and reselling online.

My main contractor is going to put in the transitions.  

Also on whether to retain the tenant or get a new one, it's almost always in your best interest to retain a tenant once you factor in loss of income b/c of vacancy period and then construction period for new tenant), legal fees, broker fees, etc. 

Honestly it depends on several factors.