You are on the right track and you even answered your own questions when he gets confused he just puts his head on his chest.
Young horses and especially WB do get confused at times when first training, the important thing is to take it all slowly. Just keep in mind that it is when this confusion is not recognised/understood that some riders will cause problems in their horse. When your boy gets worried, take him back to an exercise that he is comfortable with, get his confidence back and then re-introduce what you were aiming for.
As for him tucking his head in, when he does this try giving a one sided half halt, usually the outside rein. This may have to be quite exaggerated to start with eg a full movement of your arm/wrist, enough to let him know that his head is not meant to be down there, eventually as he starts to understand the command, you can decrease the severity and it will dwindle to a mere finger twitch.
""I don't believe in having contact with the horses mouth when asking to come on to the bit
To teach a youngster to work in a frame they actually need to know that they have you there as support. A consistant, gentle contact on the reins is more supportive to a youngster, than no contact at all, after all we are wanting them to go forward into the bridle, but if the bridle is not there.......
I hope this has helped but please accept my apologies if this has made no sense at all