More birdog business questions

I have a an idea of how I want to set my business and website up.

I want to be a bird dog or a go between person for:

investors selling and buying
homeowners selling and buying

really my question is can I birdog for not only sellers but buyers and does it matter if they are owners or investors or even other birddogs?

If a buyer (investor or non investor) contacts me and I set them up with a seller (investor or noninvestor)at that point am I crossing legal lines of acting as a realtor?

Also do you think it’s a bad idea to have 1 site for all parties or separate sites?