Not mentioned is the steerer material. The shine on the exposed steerer in the second image suggests an Al steerer. Is this so?

Al steerers don't really need an expansion or pressure plug and pretty much where ever you locate the stem (and thus apply clamping pressure) should be fine. However carbon steerers do need the added reinforcement.

Interesting that some carbon fork instructions require a short height spacer above the stem and below the top cap. This is to ensure that the stem clamp is not too close to the top and open end of the steerer. Too close to the top or if the stem extends above the steerer (as is OK with an Al steerer) can concentrate the compressive forces the stem's clamp produces too close to the unsupported and open end of the steerer and lead to a crack.

I would defiantly follow the fork brand's instructions on this detail. If you are the type to later complain about a steerer cracking from a poorly located stem (and/or poorly supported steerer top end) then have a shop do this and have them write up a service ticket for future reference. Of course this added assurance should cost something: Andy