1 No doubt about it. I really wish, though, that Mr. Trump had gone about this differently. 

I've pointed out before that as a technique of his "Art of the Deal," Trump often begins his negotiations by throwing a grenade on the floor, and after the smoke from the explosion settles, he starts the actual negotiations. I'm not quite sure if he's throwing only one grenade this time...

2 It's called the "GIUK Gap," Greenland, Iceland and the UK, and we already control it with SOSUS, nuclear submarines, and bases on Greenland, Iceland, Scotland and England. During the Cold War Russia could not access the North Atlantic from their north coast because we had that transit completely blockaded. That's why they need Crimea, for access to the Atlantic without a route that is already controlled by NATO. We do not need to "own" Greenland to take control of a sea lane that we already fully control.

3 I agree Dana; Trump went about this the wrong way. But then American Presidents have been trying for some time to do this without any luck.
You are absolutely correct Bill, but given the way thinngs are going in the U.K. and Iceland and with the Chinese nosing around there it becomes imperative to have greater control of Greenland. 
Last June the Danish Parliament amended long-standing rules that limited American access to Greenland to the old Thule base (which is now a Spaceforc base with a name I can't remember at the moment - Pufikin or something). They did this out of fear Trump would keep pushing for the island. But being able to "enter" it and being able to build covert bases and place strategic forces there isa  whole different matter. 
This article shows that Trump wanted military bases there all along and that is the driving force behind what he is doing As Dana says, Trump tosses hand grenades in then negotiates from a position of strength. That's clearly what he's doing here. From the Hindustan Times:
"However, the New York Times cited three sources to reveal key terms of the deal. The publication reported that a potential compromise under which Denmark would grant the US sovereignty over limited areas of Greenland to establish military bases has been approved. An official told NYT that Rutte had pushed the idea."
end
These are the most recent negotiations with Denmark and Trump is being offered a lot more than what he had before - and he already got half a loaf last year.
This is vintage Trump.
This also puts not just Denmark but all our erstwhile "allies" in NATO on notice, making it clear we aren't going to let them continue to screw us over, especially where China and Russia are concerned. Trump is telling them that if they cut a deal with either they may wind up getting Daned.
Your point about Ukraine is spot on Bill! The Russians need warm water ports and with Americans at that Gukky Gap it is hard to use the North Atlantic for nefarious purposes - and using the Bosporus and Dardenelles still leaves them in the Mediterranean, so they either have to go through Suez or Gibralter.