You will have a hard time narrowing down the actual server IP. This is because R* is using Akamai's "Content Delivery Network". The CDN is a bank of servers around the globe that receive your request for content. They then contact the actual servers for the data then caches it. This speeds up response times to users and frees up requests from the actual servers. Hope that explains it.
I love having the fast travel at camp. I am able to go to and from camp to where I need to in a snap. It's great when your across the map and realize you need a resupply run.
Posse members can use the fast travel at camp as well.
Posse members can contribute to Cripps butcher table at camp but only leader can start missions for Cripps. I have my posse fill their wagons then they all load up Cripps with supplies and materials.