Need some Qs answered on a level skip

[Eryna]

I've found mixed answers online but essentially here's the deal.
My brother wants to play FF14 he has base and heavensward content but has not been through the ARR story infact he's like level 10

He ONLY wants to play as DRK

So my question is, without being able to physically go to ishgard but having access to HW content could he start a buy the 60 skip for drk without a story skip and just be able to play as drk?

He can. All you need for a DRK/MCH/AST potion is the Heavensward expansion registered in your account.
I used an AST level-boost potion on a level 21 alt without any problem.