Heretek - Mechadendite atack options

By ShadowRay, in Black Crusade

While browsing though cybernetics I've started to wonder how I can effectively use several mechadendrites in combat.
We have:

- ballistic (atack as an reaction)
- manipulator (atack as reaction or standard atack)
- medicae (no indication how it behaves)
- servo-arm (atack as reaction or standard atack)
- utility ( also no indication how it behaves)

so heretek probably cannot use two ballistic mechadendrites, because he has one reaction, but how do we count the rest in combat?
Can heretek with two weapon wielder atack with his weapon and with mechadendrite? If he has multiple mechadendrites, with how many can he atack? Should he count them as Multiple Arms Trait fot the sake of number of atack rolls? What modifers and talents should count?

Also, can we use bionic arms to gain multiple arms trait?

This was kind of clear as mud for my Heretek as well, I spent the time making the ballistic mechanderite, bunged a Bloodstone on it, spent the 500xp to use it with the intent to sweep away pleb-level mooks and never really got around to doing so. Mostly because the large bitey things in that stage of the campaign had a TB that would have laughed off the damage.

Figuring I would like my reaction spent avoiding being squashed like a bug, I also picked up Step-Aside talent, however with Mechanderites I guess the two-weapon weilder talant as a variation for the implants might need to be house-ruled in.