"ke keiki kāne"
There's half as many letters in the Hawaiian alphabet as in the English alphabet which has two results. 1) when you learn short words, they will often be very similar and blend together easily. 2) There will be fewer short words and a lot of long words. Both things make learning the vocabulary just a little bit harder. Go slow and pay a lot of attention to every letter. With half has many letters, they are each twice as important.
Nope. In front of "kaikamahine" it would be "ke" even though a "girl" is feminine. There aren't masculine and feminine articles in Hawaiian. It's sort of like English "a" and "an" which changes depending on what letter the next word starts with. "The" is "ka" in front of most letters, but becomes "ke" in front of k, e, a, and o. So in front of "wahine" you would use, "ka", but in front of "kāne" and "kaikamahine" it is "ke".