I never have nor have I heard of others doing this. I guess in some places, this could work and it really depends on the market. A market that has a lot of properties can benefit from people working together, sure.
Nothing of such. Haven't done it and I haven't heard of something like that, maybe a platform or something.
Not me personally but I have known a few people to do it. It makes sense if you are trying to cover a larger area I suppose but I would much rather run solo.
I have done this a few times with success. You have to know who you can trust and who is not looking to just steal properties from underneath you. You also have to consider what business you are in. Are you simply selling homes or are you buying them and flipping them?
I would never risk it personally. I just don't trust people when money is involved. I have seen people get stabbed in the back working for the same real estate agency.