[1] The Talmud does not refer to the psalm by the (current) title of Ashrei, but rather as the opening words, Tehillah l'David.
The Rome liturgy adds to this Psalm 119:1 and Machzor Vitry (12th century) adds four (possibly five) other verses beginning with the same word ("Ashrei") (namely Psalms 119:1-2, 84:6, 112:1, and 89:16), and it appears that originally the general practice was to have more introductory verses than the two now used by Ashkenazic and Sephardic Jews.
[8] It is customary for the congregants to be seated while reciting Ashrei, as the introductory verse, "Happy are the people who dwell in Your house", describes the congregants as part of the household, not strangers or mere visitors, so they sit to demonstrate that connection.
The word ישב, here translated as "dwell", also means "sit down" (as in Exodus 17:12, I Kings 2:12, and Psalm 122:5).
[citation needed] Verse 7 (ז): It has been noticed[9] that, while the majority of Hebrew Bibles spell the first word of this verse with a long vowel - זֵכֶר (zaykher), many prayerbooks print this word with a short vowel - זֶכֶר (zekher) -- the two variants being described as "five dots" and "six dots" respectively.
"You open Your hand ..." This is a most important verse and the universal practice is that it must be said with much concentration on its meaning and with sincerity.
[12] At other times, when tefillin are not worn, in addition to the concentration on the meaning of the verse, it is a custom (primarily Mizrahi but also practiced by others) to lift up one's upturned hands as if to receive God's gifts.