Regarding the companion group and the dynamic of a group, I think Moffat's vision of the show put the story as more of The Doctor's story than the story of the companion. The most obvious version of this is found in terms of their introductions... Take, say, the introductions of Rose, Martha and Donna versus those of Amy, Clara and Bill... Rose and Martha are introduced similarly - we meet them, see their job, and the Doctor enters stage left and turns their life upside down. With Donna it's a bit different as she'd been previously introduced, but when she joins the crew in Partners in Crime she spends most of the episode alone, and much of it is seen from her POV as she hunts for the Doctor.
Amy's introduction is interesting because it also introduces a new Doctor, of course, but it's worth noting that the show opens with the Doctor, and it is
about him. Largely this is true for Smith's whole run - things happen to Amy and Rory around the fringes of the Doctor's life, but he drives absolutely everything. Clara's a weird one, like Donna, because of the fake-out introductions, but if we look at The Bells of St. John, her actual introduction, it opens with the Doctor again. Here he is - random phone call - who is this woman? In a sense, the situation is flipped compared to Rose and Martha - the companion is the mystery, not the Doctor. Bill is interesting as there's no build-up - she meets the Doctor in scene one - but again, it plays as him being familiar, and that's that.
Part of that is to do with the show being on air for so long... I think it's difficult to act as Series 3 and Series 4 did now, with no pre-titles sequence, playing the first half of the first episode like 'Rose', with the Doctor not the focus.
Anyway, my point is - this is what I think we'll see a bit more of. Back to a group focus, back to a
companion focus, hopefully with Jodie as something of a mystery that plays out over time.
I'd expect him to explore group dynamics and show character development from weakness to strength, but I definitely don't want the companions 'saving the day' regularly or even having the plot focus on their background. That has been done to death with Rose, River, Clara etc. It is entirely possible to have a larger TARDIS team but still have great stories. I'd hope he'd know that given he grew up on Classic Who.
We'll see, but I think Chibnall is more likely to be on the RTD end of the scale when it comes to featuring slice-of-life companion stuff than on the Moffat end - and the companions will
always get their chance to save the day, because a lot of kids look up to them as much as the Doctor, to be fair.
