In Romeo and Juliet, what sorts of food and drink were on the menu at the great feast?

What a feast it would have been! Appearance was just as important as taste, so dishes would have been "sculpted." For instance, the Elizabethan nobility were fond of eating swan. The bird would have been plucked, cleaned, and roasted. Then the feathers would have been put back on the cooked bird. Many foods would have been covered with gold as well. City water wasn't very clean, so most people drank wine or ale or sometimes cider.

Elizabethan-era.org.uk (linked below) describes a multi-course royal banquet:

The first course consisted of a civet of hare, a quarter of stag which had been a night in salt, a stuffed chicken, and a loin of veal. The two last dishes were covered with a German sauce, with gilt sugar-plums, and pomegranate seeds.... At each end, outside the green lawn, was an enormous pie, surmounted with smaller pies, which formed a crown. The crust of the large ones was silvered all round and gilt at the top; each contained a whole roe-deer, a gosling, three capons, six chickens, ten pigeons, one young rabbit. To serve as seasoning or stuffing, a minced loin of veal, two pounds of fat, and twenty-six hard-boiled eggs, covered with saffron and flavoured with cloves.

That's just the first course! Foodtimeline.org actually uses the banquet scene in Romeo and Juliet to describe an Italian renaissance meal. It even includes recipes of foods they might have eaten.