"Einstein’s theory" about gravitational waves could be confirmed today

[rmohr]

(Hope this is ok to post in this section, apologies if not from this newcomer)
Many of you may have seen these headlines all over the internet over the last few days:
http://www.theverge.com/2016/2/10/10958154/einstein-gravitational-waves-ligo-discovery-announcement-live-stream

I'm curious as to your thoughts:
A) If this discovery is "confirmed", what the implications might be?

B) Was it really Einstein who originally proposed the idea of so-called gravitational waves? (Or more broadly speaking, that gravitational force might be propagated by waves through some medium, which I believe would be a much older idea from the classical era going all the way back to Newton and possibly earlier)

C) What are "gravitational waves" meant to be anyway? Are they meant to be the mechanism by which gravity acts? How would pulses, ripples through the "spacetime" cause bodies to attract each other? Why wouldn't they be regarded simply as another low frequency perturbation, whether transverse or scalar, that simply 'jostle' or even repel other matter they encounter?

According to this article, gravitational waves are depicted as transverse, linearly or circularly polarized:
http://www.universetoday.com/127255/gravitational-waves-101/
But it seems there are many alternative scalar gravitational wave theories out there which fall outside general relativity.

D) I believe they are expecting to confirm these waves propagating at the speed of light. I was my impression that existing theories have predicted them to travel significantly faster than light? (de Broglie, et al)

More here:
http://www.universetoday.com/127329/gravitational-wave-sources/