Converting Single Family to Multi Family

[Nick Payton]

I am curious to hear about those of you who have experience converting a single family home into a duplex or multi family property.  

Are their certain things to look for in zoning beforehand?  

Do single family homes get zoned for multi family before a request is submitted to the township?  

What are some important things to consider when it comes to the renovation?  How expensive can this get?

Just looking for some perspective.  Thanks.