Get a garden flat spade and scrape that stuff off, or go to box store and get a floor scraper with a blade to get up as much as you can.  

My other option is to use that space to do a cheaper (no kitchen/bath) addition that ties in w the house for an upstairs media room/office and adds 500sq' to my house size.I know there are a lot of details I'm leaving out about my personal situation - but just a general answer is all I'm looking for from a more seasoned investor than myself.

You can buy them retail reasonably cheap, or at used book stores.

Local municipality is in great support of development as long as it includes Neighborhood Center (grocery store tenant) This Project will include Neighborhood center and other Commercial pads that would with tenanted by those that will help derive a sub 7 cap rate valuation. 

I always advocate for joining investor groups on social media (Facebook) for that locale or region that you're interested in.

For example, you don't want one tenant to store his collection of 1970's Playboy in the common area where another Tenant may take offense.

While I'm not banking on Brooklyn appreciation, I do think homes here are a good store of value.   

He then said, OK, then just send me and my store manager the application for now. 

Mostly social media marketing, SEO, and website stuff.

After a year of working 7 days a week, i used retirement account to store then access the funds to buy the house.