Just letting you know, that if you have a carseat and you've purchased a seat for your child, the airline will want to put that seat against the window. It's mainly cuz of the issue you spoke of - its a safety problem to block the "aisle" to get out, that's why.
I've taken a carseat for their comfort when they were small - but once my kids were big enough to sit up in the chair, I would just put them in the regular buckle and let them have the extra room in the seat to move around. Its tough for a kid to be strapped into their carseat (unless they're sleeping) on the plane for an extended period. You'll inevitably end up with them in your lap at some point for comforting, and playing with them, and wish you had the extra room next to you. The carseat takes the whole area. But you can fit it. Most airline seats have it where the arm folds up, so you can overlap the seat a little if it doesn't fit. But, unless you have a model with a really wide handle on it (infant seat style), you should be able to get it in, no problems. If you go to your airline's website, they'll sometimes list how wide the seat is, in the area where you can find out about their aircrafts. They'll give you seat width and leg area dimensions, so you'll know how much space there is all around you.
Since your child is 1, you probably don't want to take the rear facing seat. The area is so short, that the seat will get bumped by the person in front of you when they try to recline - or prohibit their being able to which will only upset them. Also, your child's feet will be right up against the back of the seat and they'll probably be uncomfortable too. If you're taking your stroller, balance the carseat into the stroller and let it do some of the work getting it to the gate.
Also, don't sit in the front row seats. Some people say wonderful things about the extra space you get, but The arms don't move up because the tray tables are in them.
Good luck! Hope this helps. Happy travels.