eslHQ - "There is" == "That place is" or "has"

Again, you're making the mistake of thinking that because a word is written/pronounced identically, it's the "same" word. As we saw with "that", a word can have many meanings and with each different meaning, the grammar may also change. So :

Are we there?

There = adverb, meaning "in a particular place already referred to" :
A : When is Anne going to New York?
B : She's already there. (there = in New York)

There isn't any hot water.

There is a pronoun which acts as another "empty" subject (do you remember the discussion about it in It's raining ?, used with the verb BE to indicate that something exists (or, as here, doesn't exist). Other examples :
There's a man in the garden!
There are some messages for you.
There isn't much to do today.