We are about to start the campaign and I haven't played in years. I do have a core set.

I went to create the shaper deck. The box clearly says that a core box is needed. However, I'm guessing you need 2 core boxes because there are 3 cards (Modded, Magnum Opus, and Data Sucker) that only have 2 in the core box but the starter deck calls out 3.

I'm assuming that FFG misspelled one of their cards and Dregdeer is actually Dregdheer?

The list only has 42 cards (or 39 is you use 1 core set as specified). However the runner card says that you need 45 cards to be legal. Do I just start off with an illegal deck?

No, they recommendation of 1 Core and 1 Terminal Directive is correct.

They screwed up the suggested decklists as you don't have all the cards available.

And finally, 42 cards is correct as the campaign adds in 3 cards.

Thanks