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As Uncle states, close contact refers to the panel design (thin, and really not very shock-absorbing or shape-conforming).
In the US, people commonly refer to jumping saddles as close contact saddles, so in my response, I'm going to assume that when you say CC, you are referring to a jumping saddle.
1) can you only use CC (close contact ) for jumping ? (the major question ; basically what im confused about )
Usually, CC in the US means jumping saddle, so yes. Really good jumping saddles do not have close contact panels, but rather wool-panels, or at least thicker foam or felt panels.
2) Which ones do you prefer: CC or all purpose ? And why ?
I don't like Close contact saddles, because of what Uncle said above. As to whether I prefer jumping saddles or A/P saddles, it depends on what I'm doing. If my discipline were jumping, and only jumping, then I'd prefer a jumping saddle. I've never been only a jumper, in fact I've never jumped higher than 1 meter. When I did jump, I did a lot of flatwork and trails, and then some jumping for fun. I preferred an A/P saddle, because it worked quite well for all the things I did. I find a straight jumping saddle difficult to do flatwork in due to the very forward flap (bent knee) and the stirrup bar being a bit far forward. I find an A/P saddle more comfortable on trails, but I know people who love riding trails in their jumping saddle. Whatever makes you comfortable. You can do low-level jumping in a good A/P saddle, just nothing too high. You can do flatwork and basic dressage in a good A/P saddle, just nothing too advanced. Note that I say "good" A/P saddle.
3) if you werent to show very much but maybe here and there (probably just jumping but maybe dressage ), which saddle would be better to get ?
If you're doing both jumping and dressage, you should look into an eventing saddle, or an A/P, or a jumping + dressage saddle. You won't be happy jumping in a dressage saddle or doing dressage in a jumping saddle. They're as far apart as you can get.