Correct ways to introduce present perfect tense?

Hi. Do you think the following shows correct ways to introduce a present perfect tense into a piece of text? Would a person be correct to say that just about any topic can be introduced in this way (ways?)?

(a group of people at a bi-monthly meeting)

A: Whew, I had a hard time getting here on subway. Did everyone get here OK? Oh, have you seen John, I haven't seen him since I got here around 2 p.m. in the afternoon? Did anyone get any call from him? I wish I could talk to him.

(another group meeting situation, possibly bi-monthly or monthly)

A: Hi. Everyone. Whew, I just had a long bus ride to here. Oh, John. I haven't seen you for a while. How have you been? Have you seen the latest movie by John Doe. I wish you had. It had a great theme and he was especially good at this film.

Also, do you think if something has been discussed/has ocurred a short while ago and that is what is being talked about now, then we can use a present perfect tense (most of the time?)? Sorry for this question being vague. I am not sure how to ask clearly.

eg,

How was the wedding? Did you see Joe there?

I was there (I have been there at the wedding - OK?) but I haven't seen him there.