If the source of LIGO's detection is a pair of black holes, can we see them using a traditional electromagnetic/neutrino/some other kind of telescope? Or can we see their effect on other stars in their vicinity?
More devices are needed to localize the sources of the signals. It's a matter of months but until they become operational, it's impossible to scan all the suspected region of the sky.
You may find some numerical details in the question of Emilio Pisanty : How many galaxies could be the source of the recent LIGO detection?
Independent and widely separated observatories are necessary to determine the direction of the event causing the gravitational waves, and also to verify that the signals come from space and are not from some other local phenomenon.
Toward this end, the LIGO Laboratory is working closely with scientists in India at the Inter-University Centre for Astronomy and Astrophysics, the Raja Ramanna Centre for Advanced Technology, and the Institute for Plasma to establish a third Advanced LIGO detector on the Indian subcontinent. Awaiting approval by the government of India, it could be operational early in the next decade. The additional detector will greatly improve the ability of the global detector network to localize gravitational-wave sources.
An Australian interferometer would fulfil the requirement of a complete network able to triangulate the locatation of the sources. It will give also some datas to measure properly the speed of GW inside the Earth.
No, because they are no longer a pair. The gravitational wave signal detected by LIGO was a result of them merging. Since those waves propagate at the speed of light, even if we were able to pinpoint the exact origin of that signal, we could only see them at the time after they merged.