Your height: 4'5" to 4'9" (135 to 146cm) approximatly (?).
Frame size = 18in 46cm
Comments:
City Bikes: They are designed for comfort and daily commuting, to go to work, to school, to go shopping, etc.. Compromise between performance, comfort and sturdiness. Often loaded with useful accessories increasing the weight.
1 speed: for traveling short distances in a mostly flat neighbourhood. If you can walk there in 30 minutes, it should take around 6 minutes by bike. Not good for going up hills, even low grade climbs are hard. - Derailleur:
Tires 26 x 1 1/2: narrow tires with small thread, for speed on asphalt.