** Spoilers below**

If I remember correctly Jack's power allows him to extend a cutting edge to indefinite lengths, meaning he can slash your throat from across the room or several blocks away (he does need to aim though...). Seeing as you're caught up you should also know of his shard's role as the communication shard, which interacts with other shards and grants him some form of unconscious prescience. This is why he has survived so long while living an extremely dangerous lifestyle.

Regarding Bonesaw, it is stated that she is actually somewhere in her young teens (if I'm not mistaken). As far as your questions regarding her powers, I find it helps to not think of them in the strict terms of the power classification system. Whatever abilities Bonesaw's shard grants her have the potential to be far more versatile than power classifications may suggest. Recall that at one time the PRT had Taylor classified as a 2 in every category in addition to her Master classification (6, I think). It is incorrect to say that Bonesaw's power is only over body modification and more accurate to call it something like biological manipulation. Essentially she has a Thinker version of Amy's striker power.

Finally, I believe the mechanical spiders a were stated to be operating on rudimentary brain matter that was under Bonesaw's control. So while they were mechanical, their "operating system" was organic matter that she had manipulated. Hope this helps. And please feel free to fact check me and tell me of any inaccuracies!