Working with a Partnership

[Chess White]

Good Morning bigger pockets team,

I have found a potential partnership, I wanted to see if anyone has any experience or can share what they recommend or did.

I currently have an LLC and Business account that I'm trying to build up in order to buy houses through the LLC and not with me personally. (Main goal)

Now I have a buddy who wants to go 50/50 on a duplex, he is willing to let it go under the LLCs name as long as we have documentation that he is half owner.

Now my question is, would that be legally binding? Do I need to make him part owner and if I do does he have access to my other properties?

Should we just do a new LLC that were both owners to not worry about it?

Could we do a partnership agreement with my current LLC and have the Deed say my "LLC and friends's name"

What questions should I be asking to ensure we have a smooth transition into our partnership?