X-Rays: Nothing comes back from the event horizon [well, because of Quantum Mechanics that's not quite true, but close enough.]
The X-rays "emitted from" Black Holes are actually the result of gravitational effects happening within a few thousands or millions of miles outside the event horizon. Here is one explanation: http://physics.stackexchange.com/questions/24958/how-can-a-black-hole-emit-x-rays. There are other reasons as well. But all of them are well beyond the event horizon.
if one could navigate space fast enough and head "outward" would there be an end of the "matter" infested universe in a sense that looking outward there would be nothing to see but darkness?
In essence, is there an outlying edge of the existing universe where beyond that point lies nothingness? Or, is the existing universe contained within a box where there is ultimately a wall at the end of the expansion?
After looking at it, I know, it's a stupid question The question is not meant in any manner of "gotcha" but rather a combination of astrophysical and religious curiosity.......Thank you