I'd also expect them to make more plans, as well as be less headstrong as to the moral qualms. The entire rush-in attitude, acquiring morphs as they go would be more adverted, and I'd think they would go on to the offensive sooner.
As far as drugs... I don't see that happening, even if they were older/mature. Too goal oriented. Maybe try something after something really stressful, but I don't see it lasting. If something goes down and they get caught up while high, or even drunk... not too good. I especially don't see Jake doing anything, but Marco might try smoking normal cigarettes.
Mature love is more likely, and as far as violence, I don't see much in the way of more, just better described/more detailed. Such things as when Erek reprogrammed himself and went on a rampage would be described instead of calmly ignored.
I don't think Tobias is gay. It was never mentioned in the books; not even hinted on. I don't know where that thought keeps coming from.