Your third paragraph, particularly, I can empathise with almost every word of, even down to starting reading Who books at five (and wanting to be the Doctor in so many ways). Very cheery on a crappy morning!

Bearing in mind the earlier thread about An Unearthly Child, it’s really too bad the script did so extremely little with Susan. How great would it have been to see Troughton saying “Susan, my dear, how lovely to see you” and then Pertwee cutting in with “Out of the way, scarecrow, she’s my granddaughter as well!” And then teaming Davison with Susan for the action, as the First Doctor got paired with Tegan. But yes, that would have raised all sorts of questions about her background and family…bugger. Well, anyway, she deserved a more prominent role than she got.

I acquired a healthy collection of Terrance Dicks paperbacks back in the day, but the real prizes were the Target adaptations written by the screenwriters of the episodes. Warrior’s Gate and Mawdryn Undead (for two examples) added a lot of additional depth to stories that were already strong to begin with.