Re: flying with a 3mo old?
It's really not a good idea to check a carseat. They get thrown around and mishandled a lot. I've seen more than one get back to the parents broken. Gate checking is better, but still not the best. You can ask them if they have any extra seats, then you might be able to bring the seat on the plane with you.
Since you don't have a bucket, this is what I'd do. Wear the baby and push the carseat around on the stroller, might have to bungee it down or something. Or, get a bag for the carseat, then you can carry it and push the baby in the stroller. Though I'm sure the carseat is heavier and much more bulky, so option #1 would be way more comfortable.
Proud Army wife and sahm to The Chickie 2/26/05
, The Monkey 6/13/08
and The Little Miss 8/15/10 Due in Aug with #4