Two questions, Sweetcorn and Brussels

A couple of questions, I have grown Thai sweetcorn, they are just now producing cobs, how long does it take for a cob to become edible? They are very tall plants. I have six weeks before I go on holiday.

My brussel sprouts are growing on the stalk but they appear quite loose, do they form firm hearts like cabbages the older they get or have I messed up? I stamped the ground down before planting.

Thanks.