1. Luffy and Kidd should get hard fights with Top Tiers, same for Law but he can also make his show with the tactical/strategic side (I'm not excluding his death during his war). After Wano I expect Luffy and Kidd to be the last real contender of the Worst Generation for the One Piece, they'll assert their presence in some terrirories of the New World (ex. Luffy with Zou and Fishman Island, idk for Kidd but he as a QG so there should be some territories under him.
About Law, I see him having a path different from the others, something reguarding Sword/Revolutionaries
2. Post Wano I'd say Luffy 3 Mlrd, Kidd 2.2 Mlrd, Law 1.7 Mlrd (if he survives). This depends on what they'll be seen doing during the war, but at the end of the day they'll be the captains of the crew that bringed down Kaido
3. Probably Kidd's, but first I want to see him go all out
4. Definitely Strawhats