nitrogen
None, but lead-acid accumulators contain sulphuric
The first IBM 702 had two 512 character accumulators.
store energy
Accumulators.
Photovoltaic arrays are used( in conjunction with accumulators - batteries - to store energy when the satellite's solar panels are in shadow).
pressurized
Most hydraulic systems do not have accumulators.
yes
Lead acid accumulators
Assuming 2 was already in one accumulator and 2 was already in another accumulator and the two accumulators were wired together for addition, 200 microseconds (one addition cycle). The values don't matter, any numbers that fit in the 10 digit accumulators can be added in that time. If the numbers are not already in those accumulators more cycles (and wiring) will be needed to get them there.
An AC accumulators job is to remove moisture from the AC system it performs this function with a package of dessicant inside it. Dessicant is a compound that absorbs the moisture around it. An accumulators job is also store excess refrigerant not being utilized by the evaporator.