I don't know what you've done for proper diagnosis yet, but jumping around where you are is certainly not going to be and easy find by guessing.
Pinging when hot/under load could be timing, could be lean, could be overheating, could be crappy gas, could be no problem at all and you're just hearing things on a loud, raucous V-twin.
'Pops under de-cel' could be lean, could be a leaky exhaust.
You haven't begun to give enough info about the bike to know but I can guess instead of doing proper diagnosis, just like you are doing. Aftermarket pipe? Stock ECM fuel map? You seem ready to jump into the ECM before checking for any actual information, so what have you done in there? Has the bike always done it? Just bought it? Done any mods recently? Does it always do it? Whats the ambient temp?
The fuel pump priming has nothing to do with injector cycles.
The black mark is from the breather fumes.
An easy :30 second BuellXB search showed me that part numbers can be found here:
http://www.buellxb.com/forum/showthr...S-LIVE-FINALLY
Here:
http://www.buellxb.com/forum/showthr...rts-Website-up!
And this is a good resource too:
http://www.buellxb.com/forum/showthr...ference-thread