Sure

"Sure" means "yes". But it's more casual. Just answering "yes" to a question can sound as if you are angry.

"Sure" also has some of the meaning of "of course" - meaning that it's obvious and expected for the answer to be "yes". But "of course" is a stronger response than "sure".

I'll take (something)

This is similar to "I'd like ___" but it's better to use in someone's home. "I'd like ___" sounds too much like something you'd say to a waiter.

whatever you have

This means "anything". If you say "I'll take whatever you have", it means that you don't care and you'll drink anything. This makes it easy for your host if they don't have many choices.