> Yes: 'hafir' and 'brjótir' sunjunctive, but 'þú fær' indicative!
> (Google 'ef þú fær' 24; 'ef þú fáir' just 3, all in subordinate
> clauses with 'að'.

From Stefán Einarsson´s Icelandic grammar, 1945, with reference to
Modern Icelandic (Hope I've typed all this correctly):

1. Real Conditions. When condition and effect are thought of as
something real, the effect naturally following if the condition
holds, the indicative...is used in both the principle clause
(effect) and the if-clause (condition). If however the 'ef' is
dropped, then a subjunctive (present, etc.) is used and placed first
in the subordinate clause.

Ég skal koma, ef ég get.
"I shall come, if I am able to."

Geti ég gert það, skal ég koma.
"If I can do it, I shall come."

2. Imaginary Conditions. When condition and effect are both
imaginary, something supposed, then preterite subjunctive (or past
perfect, or past future, or past perfect future) is used both in the
the principle clause (effect) and the if-clause (condition). Here
too 'ef' may be omitted, but the verb must then be placed first in
the subordinate clause.

Ég skyldi koma (ég kæmi), ef ég gæti, en ég get það ekki.
"I should come, if I could, but I cannot."

Gæti ég gert það, skyldi ég koma (kæmi ég).
"Could I do it, I would come."