First of all, I'm not justifying civilian deaths on the war. I will explain it from general prospective, assuming that you (and others) know that wars periodically happen.
Russia using Iranian drones because it doesn't have enough its own. Its military doctrine (published) was defensive. It means they thought "if we not going to attack anyone why would we need drones? Being attacked, we could just nuke the enemy". That's why somewhat lacks modern warfare.
Unlike US which is doing small wars periodically and needs exact, precise weapon.
Russian army attacks civilians buildings (not civilians) because buildings are often reorganized as military objects, weapon storage, garages, barracks. Attacking such structures is not a war crime as you may find from "Geneva conventions". Ukraine not always specially doing this masking. Its just because there is no other place for soldiers or weapon. Finally, Ukraine may always show a scary picture to mass media.
About this shopping center that was stroke several months ago (the one with empty parking), I personally checked on Google map, it was just next door to railway station. Besides, Google maps labeled the object as "permanently closed" about year ago. I assume it was a storage or the goal was railway station. Probably, you know that Dresden (Germany) was bombed flat by west allies at the end of the war because it was a transport hub? Was there a need for such atrocity or not, too late to judge, but destroying transportation and energetic system of the enemy is necessary and common step on a war.
Other reasons of civilian building destruction may include: Old, not precise weapon hits wrong target, intelligence reported wrong object, the missile was intercepted and just fell down.
I'm sure, the military would love to have the precision of HIMARS or that blade-rocket that killed single Al-qaeda terrorist chef somewhere recently.
But they have to fight with the weapon the have.
I already explained mass graving. Those are, probably civilians and soldiers killed during city fights. In summer russian army advanced and took every city several days with much efforts. Cities were yet with civilians. I watch youtube, and there are many bloggers from Ukrainian cities who blogs their life under shelling. Unbelievable, to us, but they say we're not going to evacuate. Because our parents old, because I love my house, because I love my animals (cats, cows), my house will be looted. They are not evacuating because they are not afraid of russians per se, and they just hope to avoid accidental strike.
Of course, with such attitude there will be accidental deaths among civilians.
The army simply engrave bodies (including russian soldiers) all to save time and efforts.
Not too much respect to dead ? Yes, sad, but reality. Russia is lacking respect to live too ????
But even the engraving with christian crosses and separate graves, and name plates were called a genocide.
How can I explain tied hands ? Well, different circumstances.. Finally I don't exclude criminal deaths. The war is the place for all kinds of bad people. Such bodies, when found, will be also buried. By my understanding nobody will bother with untying of the dead.
Please let me know if my reply was comprehensive, I'd like to get a feedback from you.