Maple, do you need translations?
"is that a crack" - a crack is a joking comment that's aimed at someone. For example, I tend to spill whatever I eat on me. So if you say at at restaurant "what will you be wearing... I mean ordering... tonight?" you've made a crack at me.
"if the shoe fits, wear it" is a common expression that means "if what has just been described applies to you, then recognize it as such." For example, someone says something about proofreading before posting so you don't post with a lot of misspelled words, and I say "are you talking about me?" - maybe the person intended it to be about someone else, but it DOES describe me... so the response to that could be "if the shoe fits..."
"take the high road" means not getting involved in a petty dispute. You go out to lunch with a friend, and usually you take turns paying. You're sure you paid last time, but this time he says that he did, and it's your turn to pay again. If you just smile and say "My pleasure," you have taken the high road by not turning it into an argument.
Was there anything else in there that needs explaining?