[Peptobismol]

the name Siva is taken from the thamizh word "red"

Sivapoo/ Sigapoo is the word meaning red, so I don't see the connection.

Has siva always been what he has today or transformed from Rudra and is there such a thing as a rudra lingam or is it the same as siva lingam?

No, Linga worship was first form of worship, but earlier Shiva has been refered as Rudra !