[Avodah] Nusach Ari (Lubav) questions

[Zev Sero via Avodah]

Two questions recently occurred to me about the L nusach:

1. Throughout Yom Kippur, every time we mention "yom hakippurim hazeh",
the L nusach adds "yom selichas ho'ovon hazeh, yom mikra kodesh hazeh".
This includes the piece between Ki Anu Amecha and Al Chet.  But there
is one exception: in musaf, in the selichos after the avodah, there is
a mention of "yom hakipurim hazeh", and on this occasion it's followed
by "yom *mechilas ho'ovon hazeh, yom mikra kodesh hazeh".  Why is this
one instance different from all the others?

2. Throughout the year the L nusach follows the Sefardi minhag that every
time a yomtov is mentioned it's followed by "yom tov mikra kodesh hazeh".
On Chol Hamoed the addition is "yom mikra kodesh hazeh".  However, unlike
the Sefardi minhag, L makes this addition on chol hamoed only in musaf
(twice) but not in yaaleh veyavo, whether in davening or benching.  Does
anyone know why yaaleh veyavo is an exception?

-- 
Zev Sero               All around myself I will wave the green willow
zev at sero.name          The myrtle and the palm and the citron for a week
                And if anyone should ask me the reason why I'm doing that
                I'll say "It's a Jewish thing; if you have a few minutes
                I'll explain it to you".