Ambull, that rootball tree is in the same area where you have all those rounds? Great! Stabilize the trunk with some rounds/logs/branches, whatever ya got handy. Get as much under the trunk as you can in several places. This is to keep the tree from moving once it is free from the rootball.
Now, if ya want, stabilize the rootball with longer stout logs/branches, wedge them in good at an angle, 3-4 of them.
Now you can get rid of that thing down near the base. Don't cut straight, you'll get pinched. Cut a wide V, just keep beavering away at it, cut some, then whack it out with a sharp axe, cut some more, hit it with the axe again. Once you get down to the stuff holding it together, the last stuff, only the axe, put the saw out of the way. The wide V helps eliminate any potential pinch.
Really look at the tree, see if it is gonna want to roll on you. If there are any big heavy branches leaning way over, you can take them off first. Brace the trunk underneath to negate roll and to keep it suspended (some at least, makes for easier bucking as well) once free of the rootball. And if it does look like it still might roll, stand on the other side
There's other ways to do it, but that works for safety. Once the trunk is separated, you can go around and knock the braces out, let it flop then if it wants to.
You might still need to do some fancy moving at some point, but that should reduce the risks.
I am not right there to see the situation, my opinion might change if I was, but that's a generic way to handle them things without a ton of equipment.
That overhead deadfall, have to see it. Might could just snatch it down with a chain/rope and a comealong. The suggestion to nail it with another stout tree is also a good one.