Hi,
I saw that on the backerkit campaign these scenario packs were advertised as being something usable with the 1st edition, too.
Was that something for the campaign only? Or can I do a first/second edition hybrid before fully committing to an upgrade?
They're compatible with 1e. Essentially a 2e scenario is some character cards (replacing the list of characters in a 1e scenario), some location cards (replacing the locations in a 1e scenario) and some clue cards (replacing the clue list in a 1e scenario). If you just arrange the cards on the table where everyone can see them, you've effectively got the same stuff as you'd see in a 1e scenario, just written on cards.
There's no special cards list so you'd have to figure that out for yourselves if you're using them. There's the odd 2e scenario that contains a special card, so again you'd have to decide how to make use of those yourselves - or just take them out, if you're not using special cards.
The main difference is that a 2e scenario assumes you will be combining the clue cards in the scenario with those in the 2e core deck - this is essentially the same as the way 1e allows you to just make up a clue, rather than selecting one from the scenario list.