What is the latest l'chatchila (ideal) time for Shacharit?
Ideally Shacharit should be completed by the end of the first quarter of the day. B'dieved (after the fact) it's valid until midday.
Question 2
Is Maariv (evening prayer) obligatory?
Maariv is technically reshut (optional) but Israel voluntarily accepted it as obligatory. This voluntary acceptance has the force of obligation.
Question 3
When is Mincha Ketanah (small Mincha) — the preferred time?
Mincha Ketanah begins at 9.5 halachic hours into the day. Eliyahu HaNavi's prayer at Carmel was answered at this time — it's considered especially auspicious.
Question 4
If you missed Shacharit, how do you make it up?
Tashlumin: pray the missed prayer in the next prayer session, adding an extra Amidah. But you can only make up once — if you missed two prayers in a row, only one can be made up.
Question 5
When is Musaf prayed?
Musaf is prayed on Shabbat and Yom Tov after completing Shacharit. L'chatchila it should be done before the 7th halachic hour — but b'dieved the entire day is valid.