Friend wanting me to collab on developing land for the first time, what's fair?

[Jonathan Jacoby]

So I have a friend who has taken some serious steps to develop a subdivision: 100+ home sites and a few commercial properties on about 50 acres. He has city approval and the plans drawn up and he is in the process of getting bids for the work.  He has bought the land and paid for design and survey work out of pocket. He has now asked me to pay the contractors for the first stage, about 24 lots, for dirtwork, sewage, roads, curbs, electric in exchange for some of the lots. At this point he has not offered me any deals just dollar for dollar value exchange when the work is done.  He hasn't decided on the value of the lots yet but he is talking around 50k for approximately .5acre lots which for our remote area seems high.  He has talked up the tax benefits that I could take advantage of by making such an investment.  I'm sure he's expecting me to come back and negotiate something more but we are both very new at this and I have no idea what would be an appropriate value for the risk and the time my money would be tied up in this. 

That is my first question what would be fair compensation for that investment? 

My second would be how to make the most of this. Before being approached to help with the development costs, I had considered on buying after the development was complete; 4 lots then having 4 homes built, selling 2 and keeping the other two to rent out. These would be my first rentals.  In the new scenario I would end up with more than 4 lots and most of my money tied up in the development of the neighborhood. I could continue to build on credit but am uncomfortable with tying up such a high percent of my capital in a single investment. I'd welcome any advice.