I would like to build my portfolio and hopefully avoid debt in the process... any ideas where to start??

That way you are applying the same process to everyone, which avoids problems later.  

When you convert a rental to personal, how do avoid taxes from the gain and depreciation recapture?

Ideally, once the rehab and construction is complete, it automatically converts to a perm loan (thereby avoid the need to refinance the property). 

Just avoid the whole issue.

That's not my approach, personally--I'd rather just negotiate a great seller financing loan for as long as possible, and avoid the headache and hassle of refinancing for as long as possible. 

I want to avoid the break up and she moves out and he stays and can't really afford the apartment? 

Government intervention: we are avoiding states that are aggressively going after landlords

The down side is dealing with your brother, which I would avoid for your sanity. 

EDUCATE YOURSELF - yes, it will take time, but will lead to a selection that better meets your expectations & avoids potentially costly surprises!