Atomic.
No, "multiple" is not a prefix. It is a standalone word that means having or involving several parts, elements, or individuals.
Gubernatorial is a word that means having to do with a governor.
There is no suffix in the word menarche. It is a compound neo-Latin word having two Greek elements: men- for month; and arche for beginning.
It means having to do with excretion.
The word you are looking for is "synthesize." It means to combine different elements or ideas to create a unified whole.
regarding
"Expertise" is a word that means having specialized knowledge in a specific field or subject.
Costal. This word should not be confused with "coastal" which means on the coast.
"Vigor" is a word that means having a lot of energy or enthusiasm.
Military
bellicose
Cerebral.