So now we know they did rely on Smith's testimony and Schori's testimony and yes, those 2 did have some hearsay statements allowed in. They also, though, testified to things they personally saw and heard, which is not considered hearsay.
The jury mentioned a few things that highlighted they did not only rely on hearsay evidence even if they perceive they did. Statements Drew made right after the murder about how he would be suspected (not hearsay) as one example. They found the 'hit man/friend' credible as well. That testimony was not hearsay either. Even though the jury doesn't think they could have convicted DP without Smith and Schori, I think it's possible they could have. But obviously hearing Stacy's few allowed statements and hearing about KS's incidents in which she told friends DP was threatening her, made a strong impression that none of them could deny. Too many coincidences for KS to be murdered by some other person, let alone a random person.
As for how the deliberations went, the jury quickly determined KS's death was a homicide. The number of bruises, the scene, all the same things everyone has mentioned. The rest of the time was spent determining DP's guilt. By the end of day #1, 11 jurors were ready to convict and 1 was not. The 2nd day's discussion allowed the holdout to reach a guilty decision.
DP has only himself to blame. His staged scene wasn't credible when examined by experienced analysts and by cops who weren't his buddies, and he was a loud-mouthed bully who hadn't really fooled anyone who knew him. He openly made threats about Kathleen and those were overheard. He tried to hire a hitman shortly before KS's murder then canceled the attempted hit after the murder.
2 + 2. Simple math, really.