Do you know what an IP is? From the looks of your post you don't, I recommend you look it up on wikipedia. To answer your badly asked question, no... well, not really. The actual wordpress software doesn't have an IP address... the server it's hosted on does.
I think you're asking about all blogs hosted on wordpress.com. Well, I've 10s of wordpress.com blogs and all have same IP...... but m still not sure if all blogs on wordpress have same IP. You can verify by checking the IPs of few wordpress blogs.
Actually they use 3 different datacenters to serve the blogs and therefore three different IP addreses: 76.74.254.126 74.200.247.60 72.233.104.124
Don't know actually. When they first started and got up to three datacenters, it was west coast, east coast, mid US. They've changed datacenters a couple of times now. (They're a target for hacking and DDoS and some datacenters have been unable to deal with that.)