Lots and lots to consider here.The main thing I would suggest is to reach out to some agents in the markets you are trying to find properties in. 

A Real Estate Agents job is to SELL real estate PERIOD.

Without a significant reputation backing you or social media reputation thats positive it is difficult to get others to do deals with you. 

I invest heavily in this area as an agent.

Most local agents know the area pretty well and can work with foundation crews to verify what they know as well.

I have been approached through an agent with a possible lease to buy proposal but need guidance in how to negotiate such a transaction.

@JT Thomson, the best way to do this is to research top luxury agents who can successfully lease your sister's place. 

Tonight, it seems to me that obtaining a real estate license in California is the best investment at the moment.Unfortunately, California has no reciprocity rule, meaning my license would be useless if I moved elsewhere–which is quite disappointing.Still, I think it would allow me to start working in real estate as an agent within a few months.What do you think?

Usually, the listing agent pays for the photographer, so the value to the client is already added.

I wouldn't listen to little time agents who have sold 10 deals a year for 5 years.