Constantinople is a crossroads between the East and West, and a vast culinary array can be found.  Venice supplies wheat, salts, and fine wines, as well as other non-food items such as fine fabrics and raw materials.  Foods can be found from as far away as Scandinavia, from where some specialty fish is brought.  Small restaurants and cafe-like stores abound.  

For drink, wine is the main item served.  It is usually mixed with honey, ginger, or cinnamon to give it more flavor.  Water should be avoided at all costs - it is usually contaminated with harmful bacteria.  Mead, a beer-like drink, is also common and is sometimes scented with herbs.

In the upper classes, if you are so lucky, food is much different.  Nobles eat meat and white bread, while peasants have porridge and dark breads.  Nobles get their pick of a vast array of meats, including all sorts of birds such as gulls, storks, vultures, and herons, pork, beef, and fish.  Most upper class households have their own stocked fish-ponds.   They usually prefer meat boiled, as it is much more tender for the toothless elders.  

In the upper classes, pastry is also very common, especially for special occasions.  Sugar is a highly-prized luxury, especially rose and violet colored ones from such places as Alexandria.  Appearance of dishes, especially pastry, is extremely important.  A fully-feathered peacock served with a spread tail is not an uncommon sight.  Another favorite is to put live animals inside cooked food.  For example, pastries might release a dozen live birds upon being cut.

Accommodations:

Constantinople has many places to stay.  If you are a guest of an upper class person, he will probably house you under his own roof.  However, if that is not the case, you have several other options.  Some monasteries will occasionally take travelers in for free or for a small fee.  However, your best bet is probably with a small inn or bed-and-breakfast type situation.  These are relatively common, and they often include meals cooked for you buy the owners of the house.  If preferred, a woman can stay at a women-only inn or boarding house for additional security.