Is it better to take off the seed heads from oinions

They are probabaly flowering if they have dried out a few times. Apparently you should remove flower heads, as the plant doesn't put any more energy into swelling the bulb as its all going to flowers.
However as the stalks are hollow, the bulbs can sometimes rot so it best to do it first sign of bud and hopefully they will continue to swell.

Growing from seed rather than sets i have read, is less likely to caused bolting- going to seed