Yes, with either of those set ups you'll clear 35x12.5's no problem. I'm running 35x12.5 Toyo MT's on just a 2.5" level and 0.75" rear coil spacers with no problems.
For aftermarket rims you will need at least a 0 offset. But you can go more negative if you want to. They will just stick out further. I'm running 20x9 -12 offset wheels. Here's a link to my thread about my install with lots of pictures for you to take a look:
Out of those two lift options I'd definitely recommend the Bilstein's with the 1.25" body lift. IMO the Bilsteins are the best way to level the front of the new Rams and provide you with a better ride quality than stock. And for the price difference between the RCX combo kit and the Bilsteins I'd definitely go Bilsteins. The only spacer I would recommend doing over Bilsteins is the Hell Bent Steel one and only for people who are looking for the cheapest option.