Whoa boy... plenty of stuff out there on this subject, but it's often hard to digest it all in bits and pieces. Lemme see if I can help.
Holster types:
IWB: Inside Waist Band, gun goes on the inside of the pants, latches onto your belt via some kind of loop.
OWB: Outside Wasit Band, gun goes on the outside of the pants, belt is probably threaded through the holster.
Shoulder rig: Well, should be self explanatory. I don't know too many people that wear a jacket all day though.
Now, for IWB/OWB you get to play with the whole placement thing. Let's say you're right handed and 12 o'clock is your belly button. Something in the 3-4 o'clock range seems to work for most guys. You just sorta have to find the 'sweet' spot.
Like somebody said, this is hard to get to in a car or when you're sitting down. Some folks do a 'cross-draw' which is where you put the holster on your weak side, but with the grip of the gun pointing forward. Imagine what it would look like at 3 o'clock and just start sliding it around your belt until it gets to 9-10 o'clock.
There's no right answers and there's no hard and fast rules. Like somebody said, what works will depend on your body and your lifestyle (ie: dress) a fair bit.
Now, don't forget: there's always pocket carry. Just drop a small revolver or auto-loader in a pocket holster, put the holster in your pants pocket, and you're good to go.
And then: "Smart Carry" (tm) is a product that basically makes a pouch or two under your beltline for you. Think of it as a fanny pack that you were with the bag actually inside your pants in the crotch area. It's more advanced than that, but works for some people.
Oh, and some IWB holsters will let you tuck your shirt over the gun, so that the only thing showing if you're in a dress shirt, slacks, and tie are the hooks coming up from inside your pants and latching onto the belt. Some are more obvious than others.
I wouldn't consider yourself with exact makes, models, or calibers at this point. Handguns are a fairly personal thing, and what one person loves another person hates often times. For instance, I'm no fan of Sigs for a carry weapon, but that's just because I don't like the idea of a DA/SA pistol. They are some of the finest handguns out there, they just aren't my cup of tea.
Oh, and even little guys can carry big guns. We've got a member on here, IIRC, that's about a 120 pound guy that carries a full-sized Baretta in his pants. He found a system that works for him, might work for you, might not. You might find a big gun uncomfortable, you might not, etc.