Starting with #1, Your looking at a reinforced concrete structure in order to achieve that type of strength. We're designing houses here in MA that go up to 140 mph (3-second gusts), which is like a Cat 3 Hurricane.
Your asking for problems of the site wasn’t prepared properly. You should have brought the fill in lifts and had each lift compacted prior to moving on to the next one. Over time that non-compacted fill will settle and your garage will be on an uneven base. Could lead to issues with the garage structure in the future. Doesn’t help that you also live in an area prone to temperature extremes. You’re going to be prone to larger frost heaving with the non compacted soil as it will allow more moisture to penetrate into it.
Because this is a weather forum. You want to discuss it, start a thread in the off topic part of the forum. The discussion of the virus inevitably devolves into political leanings and we can’t have that.
If anyone has some money to toss down, this would be a pretty damn good spot for you snow weenies. Looks like the top of the hill is around 1,900'.
https://sundayriverliving.com/merrill-hill/