And for the "final" update...
The city engineer went out a couple times to check on things. The first day it was raining a little, so he wanted to go out the next day and check it out when he could see better. The next day he just did a visual. The third time (two days later) he brought equipment to actually measure and not rely on his calibrated eyeball. lol
First, none of the cracks are due to compaction, a failure of the soil, stress on the concrete, etc. Structurally, everything is sound and all lines are even with zero movement. The crack which coincides with the side door he said is just one of those "concrete cracks" type cracks. The inner wall of the garage crack is attributed to a dry joint in the footer. He said he can see, in the footer, that particular spot is where they started the pour, so by the time they got back around it had begun to set a little. The footer cracked which ran up into the wall. As for the last one, it too is a "concrete cracks" thing, but he said I could probably expect to see another develop over the years, because it's a 65 foot long solid pour on that one wall.
As for what is being done, the crack in the long wall is being sealed 360 because it's a direct route for moisture to get into the crawl space. The crack which is on the inner wall of the crawl space has the compacted dirt of the garage on the other side. No worry of moisture there, so no action taken. The last one, which is on the outer wall of the garage, they were just going to leave as is because there's no danger of moisture getting into the crawl space since it too has the garage on the opposite side. I brought up the possibility of water resting in the crack and freezing, causing gradual worsening of the crack over the years. They didn't want to dig up the dirt on both side of the wall because of something to do with re-compacting everything evenly would be more difficult and they couldn't ensure even compaction without a lot of extra expense. (incidentally, the city engineer felt with the type of drainage they put around the house, the grading required, etc, it wouldn't be a problem anyway) We came to a compromise. They agree to expand the concrete pad for the doorstep in all directions. So, instead of a 4 foot wide and three foot "deep" (outwards from the door) pad, I'll have an 8 foot wide, 4 foot deep pad. The thought process is the extra size will further decrease the possibility of water seeping down through the soil directly adjacent to the crack....and I get a pad for the AC unit in the process. lol And yes, I ran all this by the city engineer and he felt this was a good and viable solution.
I'm feeling much better about the whole thing now that I've had several different people look at it (also had some friends who work in the industry take a look), and the city engineer gave it his blessing. My only concern, which hopefully won't be anything I'll have to think about for years to come, is spotting cracks in the future, because I'm opting for the "conditioned crawlspace". I don't know hoe things are done in other parts of the country, so for those who don't know, this is an extra insulation package in which they put a vapor barrier in the crawl space, reduce the insulation under the floor, and spray high density foam insulation on the concrete. They eliminate all of the exterior vents where the vast majority of moisture gets in, and have a fan and vent which pulls air from inside the house down into the crawlspace, then pushes it outside. I have no idea if this is an unusual thing in other areas, but it's rather common here and winds up being, in conjunction with the spray foam insulation in all walls and the extra R-50 in the attic, a great improvement upon the standard insulation package. Oh, so the reason for concern is all of the concrete will be hidden by the foam...though I suppose if an inspector can't see it, should I decide to sell, then it doesn't exist. lol However, I'd actually want to know so I could fix it and do things right.
Anyway, thanks everyone for your insight and suggestions. I didn't have access to a specialty engineer, but I got the next best thing because of your suggestions. I appreciate it!!