Should I have one website advertising both and have business cards list that I offer buy/sell realestate services and PM services.

It sounds good in theory, but in practice is highly unlikely.  

If you adhere strictly to the laws, you will be limited in the services you can offer to your relative compared to what they would get if they listed their property with a licensed agent, and they will get less money for their property working with you than if they hired an agent.

I've been surprised at properties that have passed conventional financing though...and even FHA....also, one could present 2 offers to seller--one for a cash offer and one for seller financing (at a higher price of course). 

I love the flexibility they offer for traveling professionals, military families, or folks in between moves.My main questions:Have you noticed increased demand for midterm rentals in this area, particularly from military personnel at nearby bases or healthcare workers at local hospitals?

If you can offer a nice unit that is updated for slightly lower than market value, it is going to keep your vacancy rate at a near 2% per year. 

It's a good practice to overestimate costs and underestimate after-repair values (ARV) to keep your expectations realistic.

Constructing two 4,000-square-foot duplexes on separate parcels in San Ysidro would cost roughly $2.96 million, with a market value of $6.31 million, offering a 113% ROI.

Of course there was offers to register for more courses and mentoring  and various up sells, but you will find that at any seminar. 

But it might make sense to work with folks who can offer more focused guidance on filling the knowledge gap you have.If you shoot me a DM, I can also ask around for more of 1:1 coaching opportunities.