Doe people kiss on the cheek of a person that is having thier birthday in Poland?

yes, we usually kiss 3 times (one cheek second cheek n the first one again)
we often kiss when greeting sb too
we dont have to be very good friends w/that person to kiss like that, sometimes ppl kiss while meeting each other-when bein introduced to sb (its not sth strange to do unless ppl arent of the same status n by that i mean, u wudnt kiss ur boss or sb who u dont really know n there is a big age gap between u n such)
as for gifts, its totally natural to give flowers to a man on his bday or nameday or sth like that =) we are rather a kissy n huggy nation :D

yes

Not the younger generation.

YES! we do :)

We kiss on the cheek when we say hello to someone...basically any time when we meet someone we care about ;)

Depends on whose birthday it is. I give a long French kiss to my wife.

well, traditionally on occasions such as reunions when people didnt see eachother for a long time they would handshake and while holding the hand they would kiss left cheek, right cheek, left cheek. This still takes place but not with younger generations. If the birthday person had guests coming over ( like older relatives ) then that's how they would probably greet him. The younger the less likely.