Are passport numbers verified at airport?

I've had a bit of a nightmare, lost a passport and cancelled it then later found it.

I've basically applied for replacement but times running out, I'm awaiting call back within 24 hours to upgrade it as travelling soon so hopefully all will be ok anyway!

Was just wondering if travelled with old passport would I likely make it through, its an official passport and doesn't expire for years but has been cancelled.

This is worst case scenario, hopefully I can arrange to pick up new passport at office as soon as possible.

Flying with multiple airlines?

I'm flying with United and switching to frontier for the second flight.
My question is, if I check my bag I know I'll have to go out of security, to baggage claim, recheck my bag, and to through security again. So can I gate check my bag to avoid all of that?
Does it cost anything to gate check?

It's a carry on but I also have my purse, and supposedly I can only bring one of those on the actual frontier flight

How safe is Southwest Airlines?

I will be flying southwest airlines this coming month and i was just wondering how safe the airline really is, i'm aware of the incidents around a year ago but i've also heard very good things about the airline, so i'm confused. Is the airline a good airline? (not the price, the safety aspect) thank you!

New York to Ireland?

My boyfriend bought us flights for next week Wednesday from Stewart airport in New York to Dublin ireland. I'm 23 he's 48, he said he bought the tickets and paid for? He said if I bring my American passport and i.d drivers license I'll be fine, but is there anything else I should bring? I just don't want to get there and find out I can't board… Thank you.