Etymology of a few words

[Shrinivas Gadkari]

Namaste All,

May I request the list members to provide input on the
etymology the following sanskrit words:

prakruti : prathama kruti (?)
           first creation

shiva : ?
(is often translated to mean destruction, negative and sometimes
translated as pure)
related term : shava means corpse, are shiva and shava related ?

shambhu : ?
--------------------------
sama = balance, equalize

There are many words beginning with sama like:

samadhi, samskar, samhita, samasara

Any idea if they are derived from sama ?


Thanks

Shrinivas Gadkari