He will be in front of your leg - if you're constantly nagging him just to go forward, there's a blockage somewhere along the line!
It feels as though his wither and back has raised, and he is now carrying you, rather than simply tolerating you on his back.
Generally yes, the head and neck will stretch forward into the bridle - ensure that he is stretching from the base of the wither.
His whole way of going will be loose and swinging, not forced or jarring.
If you are inexperienced in developing swing through a horse's back, I suggest you ask an experienced person to help you from the ground. They can tell you 'now' when the horse is actually using his back, so you can develop a feel for what is and is not correct.
Not necessarily, he may be falling onto his forehand. You should be able to feel him pushing up and through when he's properly rounded.
Ask a friend to video him. You can loudly talk to the camera about what you "feel" at the time, and watch it later. You'll be able to see what he looks like as you ride him and know what it feels like at that time as well.