for me it looks like this "green section" is made out of one part, that would mean that you have to cut pieces out and then weld new part on... seems tricky for my understanding. And by the way, this seems for me safety relevant...
That part with the red circle would be part of 'chassis leg' and would probably be an expensive part to buy, might be better cutting a part off another broken car.
The green part in last pic could probably be a 'subframe' does all the lower suspension mount to it?