yes, these are the questions I need to ask myself
There are flights from South America at that hour (e.g., United non-stop arrives about 6:30 a.m.; is that the flight you're on?). It's not just the # of flights but also # of agents on duty when you arrive.
Yes. Well, I'm flying on United from Rio, which stops in Sao Paulo before continuing to IAD. This is a concern for me too: more stops = more potential for problems. Not sure how the weather is in September, but last time I flew in to GRU, fog had closed the airport and I spent 4 hours sitting on the tarmac at VCP instead.
You have separate tickets. Will your bags be tagged through to Florida when you check-in overseas?
As they're separate tickets (one redemption, one revenue) I doubt it
Will you get your boarding pass for all flights when you first check in?
Probably not. Couldn't I check in for the US Air domestic flight before I leave Brazil, and I'll already have the boarding pass?
I won't need much stuff so I'm increasingly tempted to get on at GIG with just a carry on. That should save me time in IAD (and also mean I don't have to pay to check a bag)
Also, if you somehow miss that second flight, will US Airways put you on another flight at no charge (of course, even then it would be the next flight with available seats) or would you need to pay a fee, maybe even a new ticket?
I'd assume they'd make me pay for a whole new flight?
I live in the UK, and am used to dealing with our less than generous budget airlines
If I search on united.com for the dates and cities I want, and click on "our lowest fares - with stops" it gives the option of a couple of flights "Operated by - US Airways". One of those leaves IAD at 9.18am. Other sites show another flight that leaves IAD at just after 1pm. That may be a safer option, but it doesn't show up on united.com
Who knows, I haven't attempted to use the voucher yet, perhaps if I try to with a US Air flight, it'll reject it anyway. Another option could be to trek to DCA, but I'd probably get to my final destination at the same time if I caught a flight from IAD