Is it permissible to offer prayer at home, or should it be offered in the mosque?
All perfect praise be to Allah, The Lord of The Worlds. It isn`t preferable for the man to pray at home as praying in the mosque is twenty seven times more rewarding. Therefore, this should motivate him to offer prayers in the mosque. And Allah Knows Best.
Does passing wind, from the anus without a smell, invalidate prayer?
If a person is certain of having passed wind even if it was with no smell, then both his/her ablution and prayer are invalidated, thus he/she should remake ablution and re-perform prayer.
What is the ruling on giving Zakat al-Fitr in cash?
The default ruling is that Zakat al-Fitr should be given as the staple food of the land. In Jordan, for example, the staple food is wheat or rice, and the amount of Zakat al-Fitr is 2,500 grams per person. It is easy to give this amount of rice to the poor and needy, and this is the correct ruling according to all Islamic schools of thought.
However, Hanafi scholars have permitted giving Zakat al-Fitr as monetary value, considering it more beneficial for the poor and easier for the giver.
When is Istikharah (guidance prayer) Du`a offered, before Tasleem (saying asalamu alikum warahmatu allah wa barakatuh to end the prayer), or after it?
It is offered after Tasleem.