Advice on building commercial or residential

[Tom Hafers]

Hello! I am new to Bigger Pockets. This is my first post and it's a bit complicated. Sorry... 

We currently own one lot approx. 9 acres in Massachusetts. It has an existing building approx. 6600 sq ft with 7 units rented, 2 residential and 5 commercial. Additionally, we have a 30 year land lease with a solar company. The land where the solar array is was mostly unusable because of easements. I'll attach an image. The solar array is way back in the "pork chop". The previous owner had plans to build a 6 unit, 22400 sq ft commercial building behind the existing 6600 sq ft building. I'll attach that. We are thinking of building 2 and 3 bedroom apartments instead of the commercial building and taking down the existing building. I'm estimating 30 units maybe 40??? Possibly done in phases. There are so many questions built in here and so much I don't know! What are the questions I need to be asking, what other questions do you have and what advice do you have?