The use of pana/i. How often?

I'm trying to get a solid grasp on this, as it never really came up. When speaking (let's say, in Poland, being respectful, etc.) to people you wish to be formal with, how often would one refer to a person as pana/i, just in the opening greeting? End of conversation? I've read a few topics on this, but not frequency of use.

ie.
Dzień dobry pana. Jak się masz? (or replace masz using pan są? or something)

I work pretty hard on this because it's extremely satisfying learning my grandparents language. And I heard once there is no such thing as a stupid question. (though I must admit, rereading this now makes me question that)

now for my stealty practice move..

dziękuję bardzo państwu

You have to use it as a subject in every sentence.


Dzień dobry panu (Dative case after "dzień dobry", I could explain why, but not sure if you need this knowledge right now)
or
Witam pana (Accusative case after "witam")


that's a strange mix, "jak się masz" is colloquial per se, so it doesn't go well with formal speech, but I think you can use a similar verb (miewać się which is the imperfective version of mieć się, and it sounds less colloquial), then:

Jak się pan miewa?
After Pan/Pani you always use the 3rd person singular, after Państwo - the 3rd person plural.