Fenris-77, that looks like an excellent outline! You build the pace nicely there. Know your likely cast of PCs yet so you can build a Treasure Index?
You mentioned needing a hand on probabilities, hope the links below help:
Have just acquired this in PDF form as part of a preorder. It's set 5 years after the Hobbit and based in the lands around the Lonely Mountain. Characters are supported from 6 different culture
trollbridge.proboards.com
AnyDice - You can customise this to show not just the probability of passing at a given dice pool + TN, but also the probability of getting 6s for varying degrees of success.
I really liked 1e, but I think 2e is a significant improvement. I like that attributes matter more in 2e and that hope replenishes more quickly. Little things like patrons having a small mechanical benefit and useful items/mounts making treasure more meaningful mechanically help make 2e a richer, more interesting game without making it more complicated. I think they've done a good job of integrating High Elves and Rangers of the North in to 2e and making them still feel special mechanically without making them a slog to play, which they could be in 1e due to their restrictions.
For adventures: might stick with the 1e materials (easy to convert stuff, another thing to like about 2e) and run Darkening of Mirkwood using 2e rules. Also considering an Eriador sandbox campaign using the upcoming published material and some homebrew stuff, subject to having time and energy available! Raids from Mount Gram and then mounting daring expeditions to strike back against it really fire the imagination.