On top of that my g30 is what I want to take out more. Or is that only if I cast my own lead projectiles?
The requirement for a new barrel is indeed only a problem for lead bullets (whether they're commercial cast or home-cast).
In .40S&W specifically Glock factory barrels tend to bulge the brass a bit regardless of bullet type, which makes some people get an aftermarket barrel for that, but it's not a requirement, and it's only a problem for .40S&W so with .45ACP you're fine.
As to putting in too much powder - it can happen, but its not as if you're eye-balling it
. You measure your charges on a scale and its good to go. After you get comfortable with it you can move on to a powder measure (which I know I was apprehensive about at first, but I LOVE now).
I actually use a cheapo Lee "Perfect" powder measure that came with my initial start kit. It works fine. You just zero your scale, and then set the scale to your desired charge weight. Start throwing charges from the measure. If they're too heavy or light, adjust and try again. Once you get it throwing the charge you want, go ahead and throw ten charges into the pan, weigh it, and it should be 10x your expect charge. That assures that you're getting a good average (all measures will have minor variations from throw to throw, but as long as you're not shooting absolute max loads a little variation is fine). Once I get the measure set I just keep pulling the lever for the charge I want. I usually weigh a charge ever hundred rounds or so just to make sure it hasn't moved, but I never have actually had to adjust it due to this - it has always stayed put until I adjust it for a new load.
Its really, really not that bad. I tend to be a little on the clumsy side myself, and in the 7-8 years that I've been reloading, I've still never overcharged a case, never loaded a squib, and never have blown anything up. As long as you go into it intending to be careful, its fine.