[reg45]

I heard that septicemic plague is deadlier than bubonic.

That may be true, but it may also be less contagious or less easily transmitted between people.

Was the bubonic plague the Black Death? Some people say no.

Yes it was, the buboes (a symptom) caused the skin to turn black, hence the name "Black Death".

[djf]

Correct. They have been able to extract/resurrect it from tissues of people that died then. They know exactly what it was.