In many ways, Ep 7 was a homage to Ep 4 ANH. I believe that Ep 8 will be similar to Ep 5 ESB, a darker story that ups the overall danger, with more risk and loss. Likely with a cliff hanger ending again.
Luke will obviously have a major part and I certainly hope the ole V2 is back and intact, with the same green blade and ignition sound.The story takes place some 30 years later, so it won't surprise me if Luke's saber has some slightly modified design cues, but I hope it's just the same, heavily worn, weathered V2!
I did like the new ignition sound of the graflex in Ep 7,but is very different from how it sounded in ANH and ESB.