There isn't a direct subway line from Etobicoke to Downtown Toronto. You have to make a transfer.
I am not sure how familiar you are with Toronto's geography but Bloor-Yonge is in Downtown Toronto. If by downtown, you mean only Financial District, then yes there is 1 change from Etobicoke and "2" changes from Scarborough Centre.
No, BD line is going in North East direction at Kennedy and so is the general direction of Line 3. Now please don't say that it is off by 10 degrees so it is not the same direction.It isn't the same direction. You're doing directly north.