It's all done!
I only ever paid for the parts themselves and the gas it took to drive there. They completely waived any and all shop fees. I expressed my gratitude by dropping off 3 dozen chocolate chip cookies alongside my van this morning, fresh baked form the day before at my bf's family's place. Cost for the dough was under $10, and they're gluten and dairy free just in case any mechanics there had similar food restrictions as me. That made me feel good.
Strut issue is fixed--wasn't a defective strut after all, @Goshawk you were totally right it
was something not tightened down all the way. I plan to return the unused replacement struts tomorrow.
At the end of the day I got back the van with the now properly functioning front struts, new rear shocks, alignment, and "oh we noticed both your tail lights were out so we went ahead and fixed those too." With gas and cookies I'd estimate the cost at about $315 total. After I get reimbursed for the other pair of struts, that is.
I'm breathing easier now.
It's been a pretty intense past couple of days; had another crisis to deal with last night so I'm running on less than 2 hours of sleep. Van was mostly emptied yesterday so they could access the shocks, and I'll probably start to move stuff back in tomorrow. For now, I'll cushion myself with the happiness of having a sound machine running under me. It sure does drive smooth now!
One note...they said they did an alignment, though one in the back is slightly off in a manner they didn't have time to get to, that it requires a shim or something because it was bent a bit, probably from an impact or going over a curb or something. He said it was pretty minor and not something he would worry about, just FYI.
Thanks for advising me along this journey everyone, I really appreciate it!