The different meanings of such

Reference form: http://linguapress.com/grammar/points/such.htm

The word Such is used in expressions of comparison between different items, either vertical comparison (comparison of degree) or horizontal comparison (comparison of kind - similar items or examples)

• Such expresses a degree with the general meaning of so or  so much
• Such expresses similarity with the meaning of similar or of that kind
• Such as introduces an example or examples, with the general meaning of like or  for example

Such, on its own, is an adjective ; such as is a preoposition

1. Such as an adjective.

Used as an adjective, such either expresses a comparison of degree (level) or similarity.However, unlike normal adjectives, it is never used in conjunction with determiners (articles, demonstratives, possessives) except for the indefinite article a / an .

As long as there is no determiner its usage is simple and normal: such is used attributively  (i.e. in front of the noun) just like other adjectives.
Examples :

There was great confusion / There was such confusion.
  = There was so much confusion  (degree)
They are such good friends / They are such friends.
    = They are very good friends  (degree)
Such people always amuse me.
    =  People like that always amuse me / Similar people.....   (similarity)

However, used with count nouns in the singular, usage is unusual: such must be followedby the indefinite article a or an. It cannot preceed it.

Examples :

Such a mistake (not a such mistake)
    = either such a big mistake (degree) or a similar mistake (similarity)
Such a good idea (not a such good idea)  -   such + {adjective + noun} 
    =  a very good idea (degree)
Such an idea  (not a such idea)  such + noun
    =  an idea of that nature, a similar idea (similarity)

Such or so?

When used with an {adjective+noun} group, such and so are synonyms, but there is no choice. Such is required when the adjective is used attributively; so is required when it is used predicatively. Compare these contrasting pairs:
Examples :

It was so good
Such friendly people are good to know  /  It's good to know people who are sofriendly.
It is not possible to say: it was a so good idea.It is not possible to say: It is good to know people who are such friendly

2. Such followed by a subordinate "that clause"

When such is used as an attributive adjective of degree, it may serve to introduce a subordinate that clause of consequence.
   Occasionally, such can stand at the start of the main clause, but this is not a common structure

Examples :

There was such tension that even the police were nervous.
They progressed with such speed, that they finished two hours early.
This is such a good book, that I'm going to finish it by this evening.
There's such a long queue, that I'm not going to wait.
Such is the tension, that even the police are nervous.
Such was the confusion at the entrance, that several people got in without paying.

3. Such as a preposition

Such , by itself, is never used as a preposition: in prepositional use, it is part of the expression such as.  It introduces an example or list of examples expanding or explaining the antecedent.
Examples :

Our agency has represented several major bands such as the Beatles, The Arctic Monkeys and the Clash.
I visited several cities in America, such as New York, Boston and San Diego.
You should read classics such as Harry Potter before you are 15.
Drinks such as sugary colas are among the major causes of obesity in children.

Such as or like

Such as is used to introduce examples or lists of examples following a category word.. In the sentences above "New York, Boston and San Diego" are part of the category cities, and "sugary colas" are part of the category drinks.  
  Like is sometimes used in the same way : however like is more correctly used to express similarity rather than examples.
Examples :

I saw several people like Elvis Presley at the show.
   means : I saw several "people looking like Elvis", not "people" including Elvis..
Houses like Buckingham Palace are hard to find in the United States.
   Clearly, since Buckingham Palace is not in the USA, "houses like Buckingham Palace" must mean houses similar to, and not houses including