Seems a strange deal to me. First question i have is why is he...

Seems a strange deal to me.  
First question i have is why is he talking about 3,700 net acres??  In the most recent presentations Sthn Star has been presented as 4,697 net acres (which included the extension assets). Has he kept 1000 acres of the project? or has he relinquished some acreage recently??

Secondly this deal is well below the value range that Lone Star had presented.  They were working with a value of US$225 - $325m for the Sthn Star assets.  This will have blown a big hole in their investment case.... they valued the remaining assets at a range of $0 - $125m (ie a lot less that the Sthn star assets).
You can check out the valuation they had presented on pg 11 here:
http://www.antaresvalue.com.au/pdfs/Final_Antares_Presentation.pdf

Thirdly why is he taking such a large chunk of it in scrip?  What use is that? If he is serious about developing the other assets then he needs large amount of cash

Fourth how is he going to do a buyback??  He has no cash and no production and a big capex plan. How do you fund a buyback in those circumstances?