I'm GMing a cyborg campaign and I wonder, if the bonus should apply to stealth skills, too. I suppose yes - what do you guys think?

Didn't find anything in the FAQ or with the search function, by the way.

All actions a jumped-in rigger takes with the drone are considered Matrix actions, full stop.

Fluff-wise it also makes sense, the lack of filtering in between gives a more precise control of the rigged body and makes sensor inputs come through clearer.

Alright, thank you. Yet I suspect that social skills or escape artistry (humanoid drones) doesn't count, does it?

Well, technically All actions by a rigger who has jumped into a drone (or other device) are considered Matrix actions, and receive the bene t of the +2 bonus due to hot sim VR use (SR4A, p. 245) is quite inclusive. A bit of common sense still can't hurt, so I wouldn't give the bonus for social skills, RAW be damned.

Augmentation, p. 159 has the details on what Cyborgs roll for what.
I'll also note that I've written a fan supplement with available bodies, optional rules and the works; I believe it can be useful for you, if only as inspiration.

You recommended your supplement the last time I made a topic about cyborgs, too. I like it in general, although the Cyberpunk 2020 artwork is a bit cheesy/low quality.

Beg your pardon, I have terrible memory for names.
CP2020, as well as the earlier editions of SR, have the artwork (and the general) style I simply love: the eighties turned up to 11. So if it's cheesy - well, all the better.

In that case, your avatar needs a pink mohawk.

Well, it does kinda have a mohawk, it's just orange-red.