Bagel Questions

Just finished a first batch of ITJB Water Bagels and have a few questions for those of you who have mastered them. The dough recipe calls for 1 TBL 22g of malt either syrup or powder. Syrup weighs 22g but 1 tbl of powder is about 12g. Do I add 2 of the powder?? Boiling I used 2 of syrup with good results and used the ice cooling bath as per Hamelman. How long in the boil bath...they float after about 30 seconds? Is the ice bath necessary?They are cracking upon baking at 460 for 18 minutes, which while purely aesthetic ,I am curious as to the reason. I realize applying seeds will cover this but I am a plain bagel guy till I master the craft. Thanks in advance. Matt