Fitting involves insuring that the locking lugs properly engage the lug cuts in the slide, that there is not too much fore & aft movement of the barrel (replace barrel), & that the cam lug on the bottom of the barrel allows the barrel to cam down as the gun recoils & move smoothly into lock up without binding. Most factory barrels will drop right in with no fitting. Aftermarket barrels will more than likely require some attention.
I don't believe that an extended and/or ported barrel will make any difference due to the lenght or ports. Barrel quality & fit are far more important. Ports can and sometimes do adversly affect accuracy. It depends on how they are made. Too much info/opinion on that subject to cover here. As to the Federal Arms barrels that are commonly seen for sale in the various configurations, I've had mixed results. They appear to be resonably well made/machined. The 1911 barrels have been accurate after a LOT of fitting, although not the equal of a good Wilson, Brown, or BARSTO. The Walther PP/PPK barrels were a nightmare to fit. Once in, they proved to be fine also.
If you don't have a clear idea how to fit a barrel to your specific gun, please study it for a while or get a smith to fit it for you. It's not rocket science, but ruining one is no fun. Trust me. I know from experience.