Agree with your first point. He has clearly said that he wants money. Whether he's legally entitled to anything, I don't know.
I don't know anything about the planning process other than it's complex and costly.
If I'm correct Dundalk are at home tomorrow 4 weeks. I don't know the deadline for the licence but the situation will have to be sorted before then. There may only be a 2 or 3 week window.
As I said, if he holds the lease and is honouring his end with the owner of OP then he is in a strong position.
Has anyone seen the lease and its conditions? Would there be any situation or circumstances whereby the lease could be terminated?