OK. First up, let's answer your original Basic Question(s).
Can you crimp too much > Yes. An overly heavy crimp will shorten case life.
Can over crimping be hard on the gun > No. But it may get you a little extra felt recoil.
Can over crimping create unsafe pressures using Black Powder and pure lead Bullets > No.
I am a believer in a good solid crimp. A solid crimp holds the bullet long enough to get an efficient burn started. This is especially important when using reduced charges.
While you didn't ask a specific question, you did mention you were beginning to cast your own bullets to load for 45 Colt. What Bullet?? The reason I ask the bullet, most common smokeless bullets will not carry enough lube and you did mention you were using a lubed wad. A lubed wad is a nuisance. I would have suggested you start with Big Lube bullets which eliminate the need for lubed wads. Just my take.
Almost forgot. A good solid crimp, using ALL the available crimp groove will not change case life enough to spit at.