How many plants for average family:
4- 6 per person per variety

Type of plant:
annual

Best Varieties:
Heirloom varieties produce over longer period and avoid a glut all at the same time.

Sowing:
Best sown in punnets and transplanted when bigger.

Growing Habit:
May need some staking as plant gets older and top heavy.

Growing Conditions:
Needs rich soil, plenty of compost and manures.

Companions:
Beans, beetroot, broccoli, Cauliflower, Cabbage, Brussels Sprouts, dill, lettuce, lovage, marjoram, onions, peas, Silverbeet, Spinach.

Problems:
Cabbage white butterfly
Cabbage moth
Snails & slugs
Chewing insects
T oo much nitrogen can produce puffy, open flower heads
Too much nitrogen can increase damage by chewing insects.

For more information:

Broccoli
Best of Broccoli. by Gowri Aiyar. Broccoli has been around for more than 2000 years. During the 16th century, the plant was grown in Italy and France. It began to be commercially grown in the United States in the 1920s. ... The word "broccoli" derives from the Italian 'Brocco' meaning arm branch.Broccoli is related to cabbage, cauliflower ...
http://www.restaurantsweb.com/food/recipes/Broccoli/broccoli.htm

Watch Your Garden Grow - Broccoli
Broccoli is a hardy vegetable of the cabbage family that is high in vitamins A and D. It develops best during cool seasons of the year. ... Asparagus. Beans. Beet. Broccoli. Brussels Sprouts. Cabbage. Carrot ... When broccoli plants of most varieties are properly grown and harvested, they can yield over an extended period ...
http://www.urbanext.uiuc.edu/veggies/broccoli1.html

The World's Healthiest Foods: Feeling Great
Non-profit foundation providing reliable, scientifically accurate, personalized information for convenient and enjoyable healthy eating. ... Broccoli is a member of the cabbage family, and is closely related to cauliflower ... Because of its different components, broccoli provides a range of tastes and textures, from soft ...
http://www.whfoods.com/genpage.php?tname=foodspice&dbid=9