However, I have no idea where to start looking for small apartment complexes from 10 units to 50 unitsAny ideas??

Which is why anyone who is not simply parking capital and expects an apartment complex to run as a profitable business cannot make the numbers work in Vancouver (or much of Toronto) at the moment. 

Seeking a management company that manages your type of asset (SFH, apartment complexes) can be a good strategy if you feel uncomfortable managing your own.  

I hear about people buying 50 unit complexes that have never owned, or managed a unit.

It also reduces the risk that someone tries to claim they don't owe you a commission (state laws vary on how to qualify as the "procuring cause" and this can get complex fast).  

If I owned huge apartment complexes here maybe I would be concerned.

You'll need to work with an attorney and CPA to do this as there are tax complexities and securities laws that must be complied with.

Is this a single family, duplex or is this an apartment complex?

This is way too complex for an off-the-shelf/online partnership agreement.  

We are purchasing an apartment complex that the owner is unable to sell for another 18 months due to a defeasance clause in the mortgage.