Good luck! For years I've elected to drive up to 4 hours to get a direct flight to avoid what you're facing. But it's not impossible. The biggest challenge is that you have to collect all your luggage and go through US customs in Toronto.
Westjet staff are reasonably helpful, so don't be afraid to ask questions. Be aware that they cannot help you in the US customs and immigration area.
Paperwork:
* wear an outfit with good pockets or plan to use a specific pocket in a carry-on bag with all your travel documents. You will have to access your passports and boarding passes several times before you board the plane in Toronto. Keep them handy.
* carry a letter of consent from your spouse, indicating you have permission to take the kids to the US and back. If you can, get the letter notarized. If you don't have one, there is template on the Government of Canada website (look for "Traveling with Children").
* carry a copy of your hotel reservation. US customs and immigration officials sometimes ask for this, to verify destination claims.
when you get the US customs and immigration form in Toronto, fill it out completely. You will not be allowed to enter the luggage screening area until it's complete.
Navigating the airport:
* Terminal information should be on your Westjet reservation. It might be a shortened version, like YYZ T1 or YYZ T3. Hopefully you will not have to change terminals.
* You will have to carry your family and all your luggage through the airport simultaneously. Be prepared! Make sure you can drive your stroller and your luggage (or luggage cart) at the same time -- practice a home with either your luggage or a grocery cart. If you can't, you will likely have to rely on the kindness of strangers for a bit of help at the airport. Never underestimate the kindness of strangers!
* If you're lucky, you may get to use the golf cart. (Don't hesitate to ask!) However, Toronto is very busy and handicapped passengers get priority over families.
* If you're using a stroller, you will have to empty it of kids, and fold it if asked. We've been asked to fold ours, even when it was obvious it would not fit through the x-ray machine. (You can't argue with customs officials, just smile and nod and let them figure out on their own – they're almost like children.) If it fits through the x-ray machine, great. If not, be prepared for a 5-10 minute wait while they examine the stroller in detail. Note: Canadian officials may do this procedure in Newfoundland too, but not likely as thorough as the US officials in Toronto. Don't lose your cool, let them do their job.
* Once through the security, you will be asked to place your luggage on a conveyer, and then you can continue with your kids, carry-on bags and gate-checked stroller.
Carry-on packing:
* Connections make me nervous. Pack at least one extra outfit for each member of your family, because if things go wrong (late plane, lightning storm, etc.), it's entirely possible that you will miss a connection. Missing connections in Toronto is a pain, especially if there are only one or two flights each day. (I've had a couple 8-hour lay-overs in Toronto because of weather issues affecting the first legs of my flights. No, it wasn't I wasn't flying Westjet.)
* Airport officials are pretty forgiving about kids food. You can get away with pretty much anything, as long as you can claim it's kids food. Your flight situation is a bit complicated because Westjet only provides snacks and drinks, but no meals. You have to bring your own. The complication is that you can't take fresh fruits and veggies into the US, and you will officially be in US jurisdiction in Toronto. I suggest taking packaged foods like apple sauce, yogurt, granola bars, potato chips, Cheerios, etc. Sandwiches are usually OK, but I've heard horror stories of sandwich confiscation because they contained fresh meat, cheese and veggies. (Hopefully authorities are not that strict for your family.)
* Take an empty water bottle through security, then fill it at a fountain in the airport waiting area. This is especially important if there's poor weather – turbulence can force crews to stop serving beverages. You're going to spend a lot of time in the air; you and your kids will be thirsty.
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