I need some info about our upcoming international travel with a connection through the US with our 2 year old:

YEG > YOW > IAD > DOH

1. How long does US preclearance take at Ottawa airport, considering 2 of us are Canadian citizens and one is Australian with a Canadian PR card?

We're traveling AC -- arriving at 6pm. We have an hour and 20 min from when our flight arrives in YOW to our next flight to IAD. Is that enough time?

2. Do you have to take your checked luggage to go through preclearance?

3. Can you opt out of the body scanners at YOW? Do they make toddlers go through the scanners?

4. On the way back our flight arrives in IAD at around 3pm (weekday) from DOH with a 2 hour 15 min transit before our next flight to YOW. Is that enough time to clear custom and immigration in Washington?

How is the US customs and security staff at YOW and IAD generally? We've had to deal with extremely rude custom and security agents at YEG in the past. We nearly missed our flight once because they took my husband aside for questioning for having been born in one of the countries on their 'watch' list. Since then he hasn't been able to check in online for any flights -- domestic or international, so I'm assuming he's on some sort of a 'watch list'.

1. Should we expect similar treatment at YOW and IAD because of that? What happens if we miss our flight in case of lengthy questioning?

2. I've read about applying for re-dress to try and rectify security issues. Should he apply for it before we go? If so, how long does the process take? Does it help?