You can use the “Event Begin Overlap” node to detect collisions and check if the player is the one that’s being collided with the door using the “== (object)” and branch nodes, or vice versa if you wanna handle that code in the player’s character blueprint.
As for the launch character node, plug the player character into it’s target pin, and for it’s launch velocity pin we wanna use the vector that’s perpendicular the the surface of the movable part of the door. There are more dynamic ways of achieving this but I think the easiest approach in this case would be using the existing rotation variable you got there in your timer. You can make a (x= 1, y = 0, z = 0) unit vector using the “Make Vector” node, and plug it into a “Rotate Vector” node. Then get that rotation variable, incremenet it by 90 degrees, split the purplish grey pin of the Rotate Vector node and plug it into it’s z axis. Now this is still a unit vector, so to give it some magnitude, you can multiply it by a desired value. When you plug the vector type result into a multiplication node, you’ll see that the other pin also requires a vector type input. You can right click on it and change it to be float (single precision). Finally, you can plug the result into the “launch velocity” pin of the Launch Character node. Hope this helps! 