There is a lot of variation in this depending on the building type, age of the components, class of building, demographic, amenities, etc.

I've haven't lead any flips but I have learned that funding is usually the key component for a deal. 

I tend to underwrite between 14 and 18% depending on property class and submarket.Asset management is a partnership expense not a property expense so it should be below the line--a component of cash flow but not NOI.Your G&A is a bit low, you'll probably be closer to $250/unit

syndications if your accredited can be good as well. but the sponsor is the key component here.. more important than the underlying asset.I have personal knowledge of realty mogul and realty shares.. both companies that boot strapped it and are now doing quite well. 

You can get your depreciation further broken down by separating out the costs for the land, building components, land improvements and tangible personal property with a cost segregation study.

(I'll assume you are not modifying the structural components of the building...columns/load bearing walls) Sounds like you need a licensed electrician ...and you will be good.

Reasoning is that the slab/foundation block may expose these components to condensation over time, and the treated lumber will (supposedly) hold up better. 

Structuring is a major component.

I would also like this entity is scalable to add other real estate business components if possible.Can some one help with this?

I found it's always better to individually "Sub" out each component.