Is concurrent language CCS or CSP turing-equivalent in language power?
The answer to your (1) depends on what exactly you mean by "model" and by "interacting machines". The $\pi$-calculus in particular is usually deemed to be a good simplification of  the core aspects of message passing concurrency.

Regarding (2), you can simulate Turing machines in CSP, CCS, the $\pi$-calculus as well as in C. Hence they are all equivalent in terms of the functions they can compute on the natural numbers.