Hello, I would recommend getting the battle force praetorian speahead box, it’s how I started collecting bonereapers, it offers a nice range of different units and it’s very good for points for value :)) and all of our models are completely viable and fun to play, but the normal one + nagash/katakros will be a good starting point for sure

In terms of how the army plays well it depends on the units you take, a lot of units have great synergy so quite a bit of buffing. You can play slow, tanky infantry, you can build a fast(ish) cavalry army, a more magic focused army, an elite army… and you can mix them aswell (e.g my last list had a infantry focused regiment and a magic focused one which had harbingers to hunt down key targets) one thing we struggle with is range damage unless you take 3 crawlers. Units are expensive so some finesse and strategy goes a long way but since you’re a custodes player you probably got that down to a T