Here is my take on on it. Just my opinions and observations from my geese and neighbors geese and park geese.
They do need to be locked up at night the same as any other bird. I have personally lost a goose to a coon. I've had coyotes running circles around the pen after dark. They might chase off dogs that are not big or mean but an aggressive dog will likely hurt or kill them.
I have seen some geese do well with chickens (neighbors birds). Mine do well with my ducks but are locked up separate at night. Every bird has their own personality and some are more tolerant then others. Ganders are more likely to be a problem then the females but ganders can do fine too.
Breeds and non-aggressive....The aggression of them will depend on several things.
Pilgrims, which I have, are listed as one of the most docile geese. They have been much better then other breeds I have dealt with.
Even with the most gentle breed there can be problems and problem birds. They are individuals.
Males in mating season can be a problem. Hormones do a real number on them.
The parents are very protective when they have babies.
They can have a bad day just like us. Unfortunately they take it out on anyone handy. Fortunately it happens very rarely but I have seen it happen.
They are family/flock oriented. If your part of the family/flock you belong. Strangers must be driven out or shown who is boss in their minds. Just the way it is. They are capable of including a lot in their "family" though.
Much depends on how you raise them. I have a neighbor who's little girl chased and teased their geese occasionally. The family couldn't deal with them once they got to the first breeding season. The gander actively chased and nipped. He flew in my face trying to attack me when I went there. No harm to me or them but I had to tell them how to deal with him. Another problem was they thought always be nice and they will be nice back. That only goes so far. You need to stand up for your space. Things got a bit better but in the end they got butchered to end the problem.
If you or anyone in your family isn't capable of dealing with aggression when it starts then avoid getting a gander. Don't run if there is a problem because you would be training them to think they can win. Sweet talk them all you can when they are being good, but just like with children and dogs only sweet talk and no discipline usually ends in a spoiled, trouble making meany. Praise, gentleness, rules, and boundaries and as needed enforcement of the rules. Even little kids can do well with them providing they are not the sort to run away screaming.
Personally I love geese. They are smarter then any other birds I have had. More playful. More social. Easier to train. I find them more interesting. I love them tons. I praise them all the time. But when they act up I don't back down, and they do act up from time to time. Being consistent so they know what to do helps a lot.
Perhaps a few others can chime in here.