Arrow - Spoilers galore

I'm watching, and have been since the beginning. This season they're referencing or using other DC characters, but so far the only other hero seen has been Black Canary. I'm wondering where they're going with the current (apparently pre-Flash) Barry Allen arc.

I could've lived without the return of Malcolm though. And why are they using Ras Al Ghul, a Batman villain?

They have already announced a Flash spinoff show, so look for Barry to get his powers soon.