re: How would you get close to one of those things to collect antimatter?
Send probes in with magnetic funnels and magnetic field collecting areas to scoop out the material. Think Bussard Ramjet. Then the scoop ships take the precious cargo to an already set up facility for antimatter powered starships. No biggie.
As I said in the original post, getting there in the first place is the major hurdle. But once we have a decent supply of antimatter, then we can really book it through the galaxy.