What do all the Polish single letter words mean?

I saw in some Polish texts, that there are just single letters... such as w, i, and others..

How many of them are there, which ones, and what do they mean?

'i' - 'and'
'z' - with

...

w - in
i - and
o - about
z - with

that can't be it, right? I've seen w too, but i would like to know all of them. They seem to be prepositions or conjunctions(?). It would be useful to know them all, and easy because they are just 1 letter.

z - also "from"
u - at

can you give examples?

Ten styl jest ładny a tamten nie jest. - This style is pretty and the other one is not.

There is one example..

However, I thought that 'and' was 'i' in Polish...
Sorry if that is a retarded question, I am very new to this.

and = 'i' or 'a'

When do you use them? Actually, I think a friend of mine corrected me on this one time, but she never told me why.

Can 'a' possible mean 'but'? Like "This style is pretty but the other is not" ?

Martha is pretty and Eva is pretty too.
Marta jest ładna i Ewa również.
those are similarities...

Martha is pretty and Eva is not.
Marta jest ładna a Eva nie jest.
those are differences...

but = 'ale'

Hmm.. so i is used for agreement, a is used for disagreement. (That is what I am implying from your examples).

Dziękuję. (BTW, I have like 5 different keyboards on my machine, and I think Polish (programmers) is the easiest to use. The foreign words are easy to find just by clicking ALT + letter, except the ź which is on the x, but nevertheless easy).

a - and (but, while - used in comparisons of dissimilar features, actions)
i - and
o - about, at (at 5 o'cock), oh! of, by means of
u - at, in, among, ouch
w - in, towards, in the direction of
z - with, from, of, about, out of, because of, in

There is more, and there are rules how to use them but the many collocations of these, for practical purposes, make them pretty much worthy of being considered as idiomatic.