I understand the want for a multi family unit, but for your first time, a 4-plex may be more than you can chew on right now.

"When (insert protected class) at your rental downtown had a squirrel chew through a wire and fried her curling iron you replaced it".

I have it on all my properties, it's saved me big $$$ last summer when they replaced (3) old A/C units and a chewed wire (squirrel) in one of my attics.  

My total cash investment is around $15,000.I'll admit, I bit off more than I could chew with this property and took nearly 9 months to renovate due to the poor condition of the property, but now the property should appraise in at around $50,000 to $55,000.I gave my brother 20% of the "business" at this point in exchange for his help on renovating the property.Now that we have completed the property, and have it rented out, we want to begin to form our business organization and acquire more properties.We both have good credit scores, and make a decent wage for our area.

Lots to chew on in your post. 

Cons- using all of the capital, potentially biting off more than we can chew?

As for the remaining items, I'll chew on them a bit.  

Can the Baltimore City real estate investing market chew you up?  

CAPEX may chew it up.- Cash on Cash return will likely be very low.

You will never move forward if you are paralyzed by fear of biting off more than you can chew.