O.K. Here goes....I am as close to an expert as you're going to find around here...just fact. I have carried a 1911, practiced, and yes, shot with it people who desparately needed shot at the time. This is NOT fun, as most would have you believe, and explaining your reasons on the stand is humbling. Your question about different barrel lengths is a good one, and I am basing my answer on over 30 years and over two dozen 1911's and derivatives. In general it is easier to get a 5" 1911 to feed, extract and eject reliably, even with sloppy tolerances and abominable triggers. Literally dozens of competent gunsmiths are making their living accurizing and refining the 45. Anyone's 5" plain jane .45 can be made to work reliably with a little effort. Go to a 4" or 4 1/4" Commander style (other companies use different names) and reliable feeding and extraction become a little more iffy. Go to a 3 1/2" Officer's Model and fully half of those encountered will jam regularly.
Happily there are several solutions. First, you can either spend the money up front and have exactly what you want in terms of reliability, smoothness, trigger, and accuracy.....OR you can buy something reasonably close to what you want, and then address one facet at a time until you have reached satisfaction. Assuming you are not ready to drop $2,000 or more on a Wilson or Brown custom, I strongly suggest a Kimber or Springfield full sized model (or perhaps a Colt, but Kimber is better these days)...Certainly nothing smaller than a 4" barrel for reliability (compromise on ANYTHING ELSE other than reliability). Make sure the extractor is the old internal type, not the little short external one. If you have really small hands, some makers put a Commander barrel and slide on an Officers Model frame, but your little finger winds up folded under the magazine...not as good for control, but O.K. feeding.
Unless you are in police work, carrying concealed should mean getting the necessary permit, and then do a reasonable job of hiding it well enough not to offend anybody. An average sized guy can carry a full sized .45 well enough concealed; most other folks are not trying to spot a gun on you. I came from an agency that literally gave me cases of ammo to practice with, and I could carry or try anything I wanted to. Double action semi-autos are an answer to a non-existant problem. Stay with a 1911...don't leave home without it. Rather than any other auto, my second choice would be a revolver. Jurassicnarc