@Chiefjop summed it up pretty well. I would like to add a few things.
1. - Mixing it up is a must. Nothing screams "PBN" as much as 5 full articles shown on the homepage. Sure, backlinks from homepage have the most power, but it's not always worth the risk. Definitely mix it up, leave maybe 20 - 30% at the homepage.
Btw regarding duplicate content, then yes, it would be considered a duplicate content, but I've also never had issues with that, which is interesting when I think about it now.
2. - This all comes down to the quality of the domain. I've had posts which were indexed within a few hours, then posts which took 2 - 3 weeks to index. The main factor here is the quality of the domain and its history. There are some expired domains that aren't penalized, yet Google doesn't like them for some reason. To this date, I haven't figured this out. If it's not penalized, it will eventually get indexed. You shouldn't be in a hurry anyway.
3. - Yep, change the default settings, add some random plugins, change the theme, basically change anything you can. Regarding plugins, then Spyder Spanker is a pretty good one. You can also use a code to block the robots from majestic, ahrefs etc. But definitely mix it up, you don't want the same plugin on every site of yours.
4. - Learn some patience.
You will see first movement pretty soon, within a week or so. After that, the KW positions may drop a little bit, but eventually, they will rise again. Full effect takes something over a month. However, with the latest Penguin in mind, it's hard to say how these things are going to change.
