[Trombone4Hire]

A few answers:

It assumes the reader has d20 Future, as this book is an expansion of the d20 Future chapter on cybernetics. It's technically a supplement for d20 Future and not d20 Modern, which the review writer doesn't mention. d20 Future is useful even for current-day games, so you might look for a copy somewhere.

They can become pretty powerful, but they scale with Progress Level. In a far-future PL, cybertech will be very powerful, but so will other technology.

I do recall that there are three paradigms of cybertech: 1) cybertech is just another piece of equipment that can be purchased by anyone, and the primary barrier is money, 2) cybertech is meant for certain characters but not all, and it is acquired by taking feats and levels, and 3) a more existential view, cybertech represents the loss of self-identity, and cybertech requires the expendature of experience points to represent the loss of self-identity.

As for specifics, I lent a friend my copy, so I can't really give more answers.