I'm pretty sure it did not stick anything through the plasma sheet- that is impossible. You would eithe melt the thing or just shift the plasma sheet a bit. It forms as air is compressed on contact, simple as that.

What IIRC was actually done was that some antennas were placed on the back of the shuttle & its size was big enough that the plasma bubble would not fully envelope it - it would be open up to space. And that antenna on the back would communicate with TDRS satellites through this gap, enabling contact through the whole re-entry.

Starship does basically the same, just with Starlink satellites instead of TDRS.

It's a function of the shape. On a capsule-sized spacecraft, the ionized plasma completely surrounds the craft, so no radio communications can get in or out. For an oblong-shaped spacecraft, like the Space Shuttle or Starship, the descent tends to be angled such that you have a "hole" in the plasma you can get a signal through.

No, the plasma forms a teardrop shape around small craft like Orion, completely cutting off radio comms. Larger craft like starship or the shuttle which have a roughly cylindrical shape (vs Orion’s circular cross section) aren’t fully enclosed by the plasma. The shuttle had a transmitter attached to its tail for later flights, which could send back telemetry during re-entry.

It's the shape and size.

Also Orion and other capsules fall like a rock (steep reentry profile ) compared to shuttle/starship, which intentionally slow down the reentry and kinda glide (ballpark 10min with capsules compared to 30min with shuttle/starship).

tl;dr: capsules get fully enveloped in plasma due to their shape, size and reentry profile