Does touching the penis when aroused, followed by the discharge of a white then a clear viscous substance, constitute masturbation, and what is the nature of both substances, and does the discharge of the clear viscous substance without fondling change the ruling?

It is not permissible to tamper with the male organ for pleasure without intending ejaculation, and this is considered masturbation.

The substance mentioned (without intending ejaculation) is most likely madhy (pre-ejaculatory fluid). To differentiate between maniy (semen) and madhy, and how to purify oneself from them, please refer to the aforementioned fatwas.