Eric,
Don't sweat the dumb questions. It may be trite, but the only dumb question is the one you don't ask. When dealing with the tremendous pressures involved in firearms, even the most experienced will ask often and triple check the answers. ( I'm far from the most expeienced, so I check five or six times, then ask, then check a few more times to verify.).
To answer your question, it all boils down to how much you shoot, and how much time you want to invest in reloading. If you shoot 50 to 200 rounds of .45acp a month, you can get by with a basic single stage press. More shooting, and you will want to consider something a bit faster, such as a Dillon 550b. The Dillon is a progressive, meaning with each pull of the handle, you complete all stages of the reloading process. a.) Size/deprime, b.)expand case mouth/prime/charge with powder c.) Seat bullet and crimp. ( Yes the .45 acp uses a crimp, but it is called a taper crimp, as opposed to a roll crimp used in a revolver round like the .38 Special- A taper crimp applies pressure to the smooth sides of the .45 slug, while a roll crimp turns the case mouth down at the front and rolls it under. Revolver rounds have a ring in the slug for that purpose, the ring is called a cannalure(sp) on jacketed slugs, and the front driving band on lead slugs. The 45acp taper crimp leaves the front of the case mouth sqaure so the it can headspace on the lip of the cartridge.) A single stage press means you have to swith dies for each stage, and run the cast through 3 or 4 times, depending on the setup.
I use a Lee turret press, which is a variation of a single stage press. With the Lee, I size/deprime all cases at one sitting, generally around 300 or so cases. Then the next evening, or weekend, I prime the cases and set them aside in bags marked w/ case brand and date, as well as brand of primer. The next sitting, usually the day before I shoot, I charge the cases, seat the bullet and then crimp. The sizing/deprime and the prime stages are somewhat mindless, meaning they don't require a lot of attention. With a Lee hand primer, I can watch TV, and prime at the same time, checking each primer for fit by touch before it goes int the bag. The powder charge, and bullet seat/crimp stage is critical, and requires undivided attention. This is usually done when I have nothing else going on. If there is something else to do, I pass on this stage until I can devote 100%, wide awake, sober, undivided attention to it. The same rule applies to the other stages, but not quite as strict. If I go out to dinner, and have a beer or two, I will deprime/size, but never never never prime or charge any rounds. This way, I can spread out the time involved using a single stage press, and finish what I intend to shoot in pretty short order. If I tumble 50 empty cases one week, size and prime them the next week, then the charge/seat/crimp stage only takes 20 min or so for a box of 50 rounds. My Lee turret press retail for under $100.00, while the Dillon sells for $325.00. The Dillon is well worth the extra money, as witnessed by everyone that owns one. Lee equipment is inexpensive, and you pretty much get what you pay for. The Dillon is steel, while the Lee is aluminum and cast metal. The dillon, while costing 3 times as much up front, will last 100 times longer, making it a better long term investment. I'll let some one else explain shot shells, and I'm sure i made a couple of minor boo boos here, but I think you can get the general picture on center fire basics. ( Real basic, as there is a whole lot more, and even at this length, this just barely brushes the surface). Keep asking those not-so-dumb questions. I've been reloading for 20 years, and am surprised at the number of *bad habits* I managed to pick up along the way. It' an ongoing learning process.
'almost as much fun as the shooting part.
Rich