Topping a carnuba with NXT would remove most of the carnuba and at would also leave you with bonding issues which means your durability would suffer. If you want to top with NXT skip the carnuba...or you could top NXT with a carnuba like Megs # 16.
Simply claying and waxing will not remove swirls however you may temporarily fill them if you use a cleaner wax. You can use the Poorboy's SSRs by hand...they do work better with a PC, but will work by hand. I'd recommend either SSR 1 or PwC or a good paint cleaning lotion like Sonus, Pinnacle or P21S GEPC after removing the swirls before you use your LSP.