I know many people who pull the 30% from a line of credit because they do not have the down payments  and then finance the deal via a mortgage through a corporation to hide the fact that they used a LC but again you are now 100% leveraged...You are young and your risk tolerance may be higher then some but I have bought and sold many dealswhen you are playing the "no money down game" it usually never ends well....

It is very dependent on your investment goals, style, tolerance, risk factors, convenience and so much more.

Consider your risk tolerance and ability to fund a vacancy or unanticipated CapEx. 

Or because people can afford to tolerate a lower cash flow.

Everyone has their own tolerances, but 6.5% CapEx + 3% for repairs seems high.

I second @Ronald Rohde, its a difficult question to answer without knowing your specific goals (for yourself and the property), risk tolerance and local RE market etc.Are you trying to decide between opening up your own business in the second unit or is your list of business the potential tenant pool? 

.- The number of property per LLC is dependant on your risk tolerance and setup/reccuring cost for each entity.

If you have a high risk tolerance, you could also consider a hard money loan.

Would you tolerate unprofessional behavior from a subordinate or colleague at work?

I don't think we can answer that for you as it gets into your risk tolerance level.