I have heard so many different ways of saying karate on here; karate, karateka, karate-ka, karate-do, etc. what do all these mean. I really want to know, because i tend to understand stuff better when i know something of its background.

I'll jump in here before you start springing leek holes from all the arrows and darts being aimed at you right now...

short answer:
karate is kara-te
'karroty' is derrogatory for Americanized karate.
karateka is a karate practioner.
karate-do is Japanification of 'the way' or life path of karate and the 'do' was tacked on to make karate part of the family of Japanese budo Arts.
karate-jutsu/jitsu - The science/skill of karate.

you kindof need to know the basic history of karate first, read this entire thing...
http://en.wikipedia.org/wiki/Karate

...and, don't forget the following dreaded bastardizations:
"chucks", "nunchucks", numchucks", "chucka-sticks"
Correct term: Nunchaku (noon-chah-koo)

(sorry to derail but I couldn't help it)

Well, different pronunciations are common if your language is not Japanese
I'm from Brasil, and portuguese has so many vowel sounds as japanese has.
Do not worry, search and time give you the answers...