Why did you contact him and offer to buy him coffee? Why do you want to know whether he's homeless?
Why are you taking the initiative to get in touch with his sister?
You can't get out of a crazy situation until you remove yourself, and that means not "reaching out" to him or any of his family members. If you are having a lot of anxiety about his situation ... wait. It will pass. You do not need to know as much about him as you want to know right now.
As for visitation, this is what I gave my ex and had incorporated into a court order (in other words, a judge agreed with it):
I am willing to supervise one thirty-minute visit per week in a public place. Ex is responsible for initiating arrangements for a visit. I will agree to more visits supervised by a third party acceptable to both of us. That third party is responsible for contacting me directly to arrange visits. (and then a lot of stuff about SoberLink).