The Three Weeks

Is it permitted to make an engagement party during the Three Weeks?

I live in a predominantly Ashkenazic community where the “Three Weeks” are observed with no music, and certainly no celebrations or weddings. A Sefardic family in the neighborhood has scheduled a wedding during the Three Weeks.

When during the three weeks can I shave and have a haircut? What are the laws of mourning with regard to shaving?

Is it permitted to make an engagement party during the Three Weeks (i.e., before Rosh Chodesh Av)?

Shabbat Chazon brings a palpable sadness which finds expression in the haftara: “Your Land is desolate, your cities burnt by fire, from your land strangers eat opposite you, and there is desolation, like that which was overturned by strangers” (Yeshaya 1:7). While there is no explicit parallel in the parasha, Chazal saw an implied one. Moshe criticized the people of his time with the famous word eicha (how?), which we also find in the haftara and, of course, on Tisha B’av: Moshe complained: “How can I bear alone your burden, your load, and your quarrels” (Devarim 1:12). Eicha Rabba (1:1) says that this is a sign of three stages of eicha pronouncements, like a noblewoman who had three attendants who saw her at different stages: one when she was in a calm state (corresponding to Moshe), one while in a dangerous state (Yeshaya), and one in utter disgrace (Yirmiya).