Should I manage the construction or hire a GC?

[Rick Soto]

Looking for advice on the following,

After 2 years of my first investment, I am now getting ready to make my next move on the real estate world. I am really interested  in the idea of building a 3/2 sfh or a small 2/1 duplex, my 2 questions are these:

How does the financing part of new construction work? 

Is there a big gap profit wise, between hiring a GC and handling the construction myself? 

Thanks in advance!