Ok, first point. If you want to build one muscle, you have to build them all.
There are many reasons for this. One, it prevents muscle imbalances. Only training your chest and not your back will mess you up in the long run. Secondly, there is obviously the aesthetic aspect, you want to keep in proportion.
Another point, to all those saying you should do push ups...are giving you bad advice.
The best movements for chest are BB/DB bench, BB/DB Incline bench, paralell bar dips and to some extent DB flyes and cable crosses.
Basically, to get anywhere, you need to be using weights.
You can get progress with just bodyweight stuff, but no one in their right mind would say that you won't get faster and better results with free weights.
As far as the benefits of various chest exercises. All of the exercises I mentioned above are valuable. You body needs variations in stimulus to grow. This can be done in many ways, changing exercises, tempo, rep range, rest time between sets ect.
BB bench, the main benefit is you can use the most weight. You will never DB bench as much as you can BB. The stimulation of heavy weight will not only increase your strength but your size too. To focus more on your chest, take a wider grip, but beware, a grip too wide will damage your rotator cuff.
The downside of BB is that your delts and triceps are involved alot, and the short ROM (relative to DB).
DB bench are in my opinion the best for chest, as you can get extra ROM at the bottom, you can really stretch your chest and destroy some more muscle fibres. There is also the benefit of using more 'stablizer' muscles, as you have to balance the two DB's. Another benefit over BB bench is that you do not need a spotter.
There are three general positions for bench, both BB and DB, are flat, incline and decline.
The pec as a muscle has two regions, upper and middle. There is no lower chest.
Along with this, you cannot
shape a muscle. You can make it bigger, but not change it's shape.
With chest you can emphasize the middle or upper.
Incline bench will put more emphasis on your upper chest, flat on your middle. Decline is not that valuable for chest, more so for tricep work.
Parallel bar dips are another great and underrated exercise for chest. Make sure to get full ROM, but this may hurt your shoulder a bit. Lean foward and keep your knees bent to emphasize your chest over your triceps.
DB flyes and cable crossovers are good exercises to finish off your chest workout with. They both isolate the chest better than the above three exercises (as no triceps and less delts are involved) but you cannot use as much weight, not nearly as much.
I've probably forgotten alot here, and remember you need to be doing squats, deadlifts, DB/BB rowing, doing pull ups or chin ups, some sort of overhead press, some tricep and bicep work also to get the full chest development possible.
Not even to mention diet