Missed the prayer for rain

With regard to the prayer for rain, if a group [of people] enter [the masjid] and [find] the imaam is giving the sermon, after already having just completed the two rak’ah prayer [for rain in congregation], should they [now] offer the prayer [for rain themselves] or should they sit down [with the rest of the congregation] for the sermon? Also, is [the rain prayer] to be made up [if missed]? And [if it is], should they offer the prayer in congregation?

Slaughtering sacrificial animal has no connection with being discharged from state of ihraam

If I was performing the tamattu’ hajj, and [bought a sacrificial ticket by] paying the bank the price of the sacrifice, and they told me the slaughter shall take place on the first day of ‘Eed (10th Dhul-Hijjah) – am I thereby discharged from the state of ihraam after stoning al-jamarah [al-kubraa], the tawaaf al-ifaadhah and the sa’ee?