Even if I tell you you'll probably not know it, so I just won't tell you.
Even if I tell you you probably won't know it, so I won't say.
1) & 2) "言っても分からないと思うから言わないどくわ" という意味です.
> 言っても：Even if I tell.
> 分からないと思う：you'll probably not know it / you probably won't know it.
( will probably not = probably won't = おそらくない )
> から言わないどくわ：so I just won't tell you / so I won't say.
"so I just won't tell you" が "言わないどくわ" の訳出ですが、そうしたら "tell you" を繰り返すことになりますので "so I won't say" の方がいいと思います.
I don't think you would know even if I told you, so I'm not going to bother.
この場合、次のような言い方ができますよ。
A: What city are you from?
「出身地の市はどこ？」
B: I don't think you would know even if I told you, so I'm not going to bother.
「言っても知らないと思うから、言うのはやめておくよ」
ご参考まで！
モロッコ 
カナダ 
