Yep, exhibition is just for pickup and play. Although you can change sliders and shuffle players around or edit existing players to be bad or good just to experiment and fool around.
Franchise is for playing a team through one or multiple seasons, which you can play, or sim all the games for more of a fantasy/manager type game.
Diamond Dynasty is a wild new thing they added this year where you create a completely new expansion team and name it, design the logo,everything, and play a strange but fun card system and play online if you want as well.
As for the pitch abbreviations you're talking about, 4SFB is four seam fast ball. Just a balls-to-the-wall, straight fast pitch. For most pitchers (but certainly not all), this is their main pitch (in the Show, X is the pitch that usually gets used the most, then the one assigned to the circle button, then triangle, then square).
CH is changeup. That's a slowball, basically, and it's usually used (in real life and in the game) to sneak in a strike on a batter who has seen a few fastballs in a row. If they've seen a 98 mph pitch twice, then suddenly the pitcher throws one at 68, they'll swing too early. Of course, a slow pitch is easier to hit in general, so it's best to use them only as a surprise. Although occasionally, throwing a changeup on the first pitch is a good strategy, because really nobody expects that.
A curveball (CV in the Show, I think) is a pitch that has some downward movement on it just as it enters the strike zone. So this either causes the batter to miss it, or maybe you can throw it above the strike zone and have it enter just as it gets there so the batter doesn't swing, thinking it's a ball and realizing too late that it will sink low enough to be a strike. Or throwing it low so they swing even though it drops out of the zone in the end. The best pitchers can throw one that goes from over the strike zone to below it, sometimes called a 12-to-6 curveball (like the positions on a clock). This is represented in The Show by four arrows straight down. A curveball is pretty slow, too, so like a changeup, deception is a big part of the strategy in using it.
A slider (SL maybe?) is a ball that has some horizontal movement to it. Same caveats apply as with the CH and CB. Although a slider is usually faster than the other two.
A 2SFB is a 2 Seam Fast Ball. It's a fastball like the 4SFB, but does have just a little bit of movement on it. In real life, it's harder to master than a Four Seam Fastball. And it probably tends to be
just a touch slower, I think.
This (and the links it includes) is probably a good read:
http://en.wikipedia.org/wiki/Pitch_(baseball) The term "breaking ball" or "breaking pitch" just means a pitch that has movement as it approaches the zone.
