Howdy
With any revolver, you pretty much have to line the cartridges up straight with the chambers for them to drop in, or extract. With a 45 Colt SAA, there simply is not enough room to open up the loading gate enough to allow cartridges to slip into two chambers at once, without cutting pretty seriously into the frame. Have one in hand right now, just not enough room. Maybe with a smaller caliber, but not with a 45.
Besides, who in heck would want to do that? Not me. Simple enough to hold the gun in the left hand, rotating the cylinder with the thumb and forefinger, and pop cartridges in one at a time.
Regarding not using the ejector rod; I wish I had a dollar for every time I have stood at the unloading table at a CAS match while somebody is banging the butt of their gun on the table to try and shake empties out. I usually ask them what they think that thing under the barrel is for.
Absolutely not enough room between 45 Caliber rims for the firing pin of a Modern Colt to sit between rims. Tried it a while ago to see. Oh, the firing pin will drop down between the rims, but it is barely protruding beyond the case head, and it is easy to rotate the cylinder so the pin rides up the bevel of the rims. Then the pin will be resting wherever the cylinder stopped rotating. Even worse with 45 Schofield rims. I'm sure you can do it with a 357, but not with a 45, 44-40, or 38-40.
No, it won't hurt anything for the bolt to be resting against the cylinder, the split trigger/bolt spring will just be trying to push the bolt up, but it won't hurt anything. Of course in doing so you have violated the rule about always bringing the hammer to full cock before lowering it. If you lower the hammer from half cock, which you would have to do if you lower the firing pin between rims, the bolt will be pressing against the cylinder, and any subsequent rotation of the cylinder will help create a line around the cylinder.