All of these are great options though I think the most important ingredient that we'll need at this point is a compelling plot. We already know Tony Daniels is going to deliver on the eye candy and now we just need a story that will keep us on the edge of our seats. Deathstroke needs obstacles to overcome all while showcasing his tactical prowess. We need to see Slade thinking ahead of his enemies and surprising the audience with the tricks up his sleeves.
Aside from that he needs a compelling antagonist. The closest we came to Deathstroke having a recurring enemy in the previous run was the mercenary "Legacy" who continued to resurface due to particular reasons I won't spoil. Pin Slade up against someone people will remember, someone that will make Slade a better mercenary for the experience of shedding their blood.
Have him interact with more heroes and villains. The possibilities are endless when you have such a gray character like Slade.
Give him a fair sized interesting supporting cast. It can be like Green Arrow's 2 or 3 people behind the scenes. I think that was one of the main things the previous run suffered from. Deathstroke was always on his own and occasionally interacted with Peabody who dropped off the face of the earth entirely once Liefeld and Jordan stepped up to the plate. We need Slade to bounce off of someone and not clutter the pages with thought boxes.
Lastly, we need to get away from entire arcs finishing with "It was Slade's kid A,B, or C the whole time! You know, because they hate him!"