May one attend the second day of Rosh Hashanah at a location with prayer experts if the first day shofar was blown elsewhere?

Does the four-amot waiting requirement apply when one intends to pray a second prayer at the same spot rather than returning to one's original place?

Waiting Between Prayer and Eating

If one prayed a second time intending it to be voluntary due to doubt, but then one's intention or conditions change mid-prayer, may one continue praying?

Rain Prayers

If one prays the make-up prayer first and the required prayer second, has one fulfilled the obligation?

Missed Prayers

When praying Shacharit twice for a make-up, must one eat before the second prayer?

Missed Prayers

When one bows during Zokhreinu or Mi Kamokha on Rosh Hashanah/Yom Kippur (insertions in the first and second blessings of the Amidah), must one straighten up before the blessing's conclusion?

Mashiv HaRuach — Wind and Rain

After saying the blessing with rain mention 90 times (corresponding to 30 days × 3 prayers/day) on the first day of Pesach, what presumption applies if one later doubts whether rain was mentioned?

Rain Request (V'Ten Tal U'Matar)