Why CCl4 does not dissolve in water while SiCl4 does?
$\ce{SiCl_4}$ does not quite dissolve in water; rather, it reacts with water. So does $\ce{CCl_4}$, albeit extremely slowly, so for most purposes one may safely assume it doesn't. The difference is mostly due to the atomic size of C and Si. Smaller С atom is completely blocked off by four bulky chlorine atoms, so the water molecule can't reach it. Larger Si is easier to attack.

Another factor is that silicon is a less electronegative element than carbon, so that the Si-Cl bonds will have more polar character.

Whether or not the d-orbitals of silicon contribute significantly to the transition state, is (IMHO) a question of secondary importance.