Go to Ruger's website and request a owner's manual
100-350 USD or so.
Contact Ruger through their website. IIRC, Ruger has information on their website to check date of manufacture.
Ruger and S&W come to mind.
.45 auto and .45ACP are the same round.
Nothing, .45 auto is just another name for .45ACP.
Both are fine weapons. What will make it "better" for you is subjective. If you want an opinion, I personally would go with the Ruger because it's caliber is .45acp, plus, Ruger has a reputation for building their weapons like tanks.
Nothing, they are two names for the same round.
You can get a manual for free at Ruger's web site.
Is it a revolver or semi-auto? You can go to Ruger's website to look up the serial number.
No
Ruger is one.
You can request a owner's manual at the Ruger website.