Rune Knight:
We will be starting you all off as 1st years, yes.
1) I don't see why not. Troublemaker sounds like they'd have proficiency in Thieves' Tools, but if there was something else you wanted then you can do that. I'll add it to the house rules.
2) I don't see why we can't do that, either, since you're trying to stay true to your character. Choose Wisdom or Intelligence, and that is Seamus' new spellcasting ability; it doesn't change anything else, though, so you still have proficiency in Charisma saves, your available skill proficiencies are based on the Willpower caster as written, and so on and so forth.
Fair enough and thank you. :)
Thieves' tools would make the most sense for Troublemaker in general but I have something else in mind that makes sense for Seamus for... reasons... :)
We're gonna need a place to put our character sheets.
Linear vs Sandbox?
I think my preference would be sort of a compromise between the two. Leading with sandbox that segues into linear when we grab an important story hook. If that makes any sense...?
I don't have any specific suggestions for teachers or faculty but one or two of them will have more contact with Seamus for... reasons... :)