B) Unless you also raise your lower floor landing by an amount equal to
the thickness of the added laminate and also raise the upper landing
floor height an equal distance, your top most riser and bottom most
riser will exceed the minimum variation for risers in a set of stairs.

This is a good point, although the OP discussed using a 5/16"
laminate, so if the current staircase is perfect (to within a 1/16"),
the result would not be a violation. But this bears paying attention
to. Maintaining equal riser heights is one good reason to consider
replacing the existing treads (plywood?) with new hardwood treads of
equal thickness.

It appears that any alteration you make to these existing stairs may
require you instead to replace the entire stair unit since the current
risers and potentially new treads will not meet IRC 2003 code. (Section
R311.5.3 Stair treads and risers.)

Perhaps it's naive, but if someone is just applying a finish material to
an existing stair case, which doesn't change rise or run, I wouldn't
think that would trigger a requirement that the stair case be rebuilt
to current code (should the 2003 IRC be operative).

Cheers, Wayne