I like this site for calculating where you line up strength standard wise. It's not perfect but I think the numbers it gives are pretty reasonable.
As for your question, I'm not sure of my actual 10RM but the last weight I lifted for 10+ reps was I believe 112.5kg, @ 79kg BW.
Yes, that's a 1RM figure.
Don't worry too much about how you stack up against standards, just try to make sure you're making progress over time. Follow a reputable program for guidance until you know what works for you.
If you want to squat with less back involvement, you can also try belt squats instead.
Yes, it’s 1RM.
Some people elect not to test 1RM due to injury risk. With that said, as you do more reps, your form can break more than it would with a 1RM, so it’s really about what your priorities and risks are.
Depending on your age (<50ish, or so), I wouldn’t consider 1.5xBW to be a lifetime goal; you’ll get past that with training (I’m chasing 2x squat, 3x deadlift myself). A rough estimate from one source is that your 1RM could be over 150kg. You do 3x10, so it’s not a true 10RM.
Whether it’s light or heavy, what matters is that you’re out there working.
What does Tom Platz say ?
I think you're seeing 1RM ?