My take...
1. The story must be streamlined to fit something like forty or fifty hours into about two. The outline sounds like it is going to accomplish exactly that. One house instead of a complicated history of two, for example.
2. All it takes is for Barnabas to cheat on Angelique. Even if he doesn't think of it as cheating--any bets she'd disagree?
3. I'm so hoping no one is a reincarnation of anyone. Especially Josette. It is a very old and by now boring cliche, which incidentally was nowhere present in the original series until near the end of 1897! Victoria was not Josette remember? Josette was a ghost, and Maggie just happened to look like Josette. The later versions that went with this old chestnut frankly weakened the whole story.
4. Professor Stokes is a great character--but he really has next-to-nothing to do. Especially when Barnabas first shows up (we didn't meet him until after Vicky returned from the past, if you recall).
5. Okay, logistics--if the Collinwood manor is something like a ruin, then for all we know Elizabeth & Company are living in a nice large modern house not too far from the estate. Willie is probably the caretaker of the place. Thus when Barnabas shows up, he can easily stay in his old home (and there's some lovely potential for melancholy right there btw) without anyone really noticing--at least at first. But if he offers to restore the place, I imagine the Collins family would be pleased to let him do so. Doesn't really take much to see how this can work. But at the same time, you can see how some folks would always be sneaking onto the old estate, maybe smoking pot and stuff. And if anyone were watching, seeing movement in the old place could spark rumor or action or just plain curiosity. Lots of potential there.
6. Personally, I think setting it circa 1970 is a brilliant idea. If somebody showed up today and told anyone "I'm your hitherto unknown cousin from England come to stay" the first thing they'd do is do a google search. Which in Barnabas' case would turn up nothing. Nada. Zip. Same thing for a credit score. But in 1970 someone might be able to pull it off.