A christmas light bulb question
Ohm's law applies and those bulbs are indeed just simple resistive loads. To get the series current, first derive the equivalent resistance at rated voltage and current for each lamp type. Add up these resistances and from that and the applied voltage to the entire segment derive the series current.

The bulbs with a lower voltage rating will most likely shine brighter than the higher rated ones.  Since both types are in series, the same current passes through them.  However, the energy dissipated (in the form of light and heat) by the filament may be different.

From an application note for aerospace lamp components: 


  Design Volts: The voltage for which the lamp was originally designed.
  All other ratings (amperes, brightness, and life) are measured at this
  voltage, and can be changed by rerating the voltage.
  ... 
  Candlepower is directly proportional to the 3.5 power of the ratio
  of the applied voltage, and can be increased at the expense of lamp
  life.