How is 2player bomb control unlocked? Snow bomb in 2p? 
Or is it not added, and is 51 or missing item related?Nobody knows.
Also, what is the helmet of volleyfest and what is it supposed to do?It's a Soccerfest-exclusive item. Lets you upkick really high.
Is the last level in the training mode orderable, and is that the key to opening the well, rather than kicking the baddybombs onto the bucket?I can not answer about the order, though probably not, but it is certain that it's impossible to open the door.
Is the missing item in Hammerfest the helmet, some sort of co7, or is it pd51 related?Pick what you think it is. The helmet theory is very plausible, actually.