It's an "only me" thing, It's kind of hard to explain, but I draw my magic from cities, and in turn they'll... well, swallow me up and spit me out in another city. So I can go to NYC and ask for a lift to London and I wind up there. Needless to say, it's not exactly possible to take anyone with me. Apparently it's hard on the mind, seeing through the 'eyes' of a non-living entity.

I can carry about a duffel bag's worth of weapons and explosives... so I guess as long as I can (barely) lift it, I can teleport with it. I haven't really tried testing the limits. Getting stuck inside a city is NOT something I want to repeat.