Alright, "Koko", "Kore", and "Kono" should be pretty easy. Koko is location, Kore is this, and kono is 'this [something]'. Now, my question is, in some cases, can you substitute "koko" for "kore" in some somewhat informal situations. Two sentences I've heard are, "Koko mada da"(or made, kinda hard to tell from where I heard it), and "... koko ga eigo de hanashimasu", which is subtitled as "I'm going to say this in English".
EDIT: And on a side note, I'd just like to thank the people at this site. I've gotten pretty far in Japanese, even if I still can't understand half of what I hear, and whenever I've gotten in a pickle, in most cases, the people here have managed to get me out, even if I've only made about 30 posts so far.