@Joshua Manning - this is definitely an ambitious plan and would be a great way to learn a lot from a variety of markets.  

You can do a variety of things, require the property have one vacant unit as part of the purchase, putting it on the seller to empty a unit.

I've been blessed to connect with and work with a variety of talented people in this market.  

If so, then let your realtor do what they normally do and you guys can discuss it to work out the details of price and terms.However, if you're looking to acquire real estate investment properties, then everything depends on such a variety of factors you really need to have a specific strategy and goal in mind.

It will help you to know there are many forums available on a wide variety of subjects. 

It is called Craig's List.I don't know of any such commercial platform and would never be an investor on such a platform.The crowdfunding sites provide a variety of services to investors that all cost money.  

I know BP has a list of books they recommend covering a wide variety of real estate topics (I've read several of them and they've been very helpful).

As for neighborhoods, you will see that multi-unit properties are in pretty defined areas, so you don't have a huge variety of choices.

But, if you fence it and allow a wide variety of pets, you may have an interesting niche.You may be able to get great cash flow, but you are probably going to have to work for it.  

Mortgage brokers are familiar with a variety of different loan programs and sometimes have connections to private lenders as well.