Also, Too - także, też, również

When do you use each of them? Or are they all interchangable...meaning the same thing depending on what sentence they are used in?

Yes you can use them as you want (in most cases).

Także can be used as therefore or thus. Też is standard but również is the word of choice in shops. Dziękuję, dziękuję również.

Most commonly used is też.

Również is often used to express that sth is "mutual".

Like Seanus said:

- Dziękuję
- Dziękuję również

Same as 'Dziękuję nawzajem!'

There is a small difference between “też” and “także/również”. The first word is less formal. If you overuse “także/również” in everyday language it can sound funny for native speakers. Do not forget the difference between formal and informal mode is też important. Not only the meaning matters (-:

Is then 'również' as a response to 'Dobrego weekendu!' or 'Dobrej zabawy!', for instance, therfore more "formal" than 'nawzajem' in the identical context?

:-)

I'd say nawzajem in that situation, Lyzko. You could say 'ja również życzę Ci miłego weekendu' but nawzajem is shorter.

Or "wzajemnie".

Thanks, Seanus! That sounds about right.

I would say we have a similar situation



are a bit more formal ( "ja również etc." much more) than just "nawzajem"

I don't feel the formality when I say it. With some words you can but not those ones. I think they are often situation specific.

formal informal is a bit coplex thing in Polish:
Let's have first names:

Przemysław
Przemek
Przemuś

The first form is the most formal
and then the grade of formality is less and less.

Of course you can say Przemysław is formal (this form you can find on ID)
adn the rest is informal. But I can feel a difference.

I would never say to my close friend "wzajemnie..." or "ja również..." because he or she would answer me: You are funny man (-:

How about Jakub, Kubek, Kubuś....?

Jakub
Kuba
Kubek/Kubuś

Usually the less formal version has a few equivalents. They are I would say equal.

We Polish people like to express our feelings (positive and negative) that is why formal and informal mode is so complex in Polish.

"We Polish people like to express our feelings..."

I've noticed. LOL
Get six Poles in a room and you'll have seven or more opinions.
What's a meeting of the Swedish parliament? - A concensus.
What's a meeting of the Polish parliament? - Utter chaos
))))

To quote a 19th Century diplomats' joke:

One Pole, a charmer
Two Poles, an argument
Three Poles the Polish Question

There's a similar one about the Austrians.lol