Is the prayer of the one praying alone or in congregation while having a piece of candy in their mouth considered valid or not?

What is the ruling on one who sneezed during prayer? Should he say 'Alhamdulillah'? And is he permitted to say 'Yarhamukallaah' to a sneezer?

What is the ruling on a wife who interrupts her prayer when her husband arrives home, and finishes it in another room?

I`m always absentminded in obligatory prayer. I even finish prayer without being conscious of it at all. What should I do in order to attain submissiveness {khushoo`}?

While praying, my wife realized that part of her hair was uncovered so she covered it. Is her prayer valid since covering Awrah is a condition for prayer being valid? Moreover, if this recurs out of forgetfulness, what should she do?

Sometimes, a mother would raise her voice while praying to warn her child and those around him against a certain danger, such as a heater or an electric plug, through Saying Allahu Akbar or Sami' Allâhu Liman Hamidah Loudly. Is this permissible? In addition, does this affect the validity of her prayer?

A heater is turned on and set in front of the people praying in one of the Masjids, but the Imam insists on turning it off under the pretext that it isn`t permissible. What is the Sharia ruling on this?

Some people tend to move a lot while praying. What is the ruling of Sharia on that? Some even join the congregation late and after the Imam makes Tasleem, they take many steps towards a Sutrah-a pillar or a wall-to continue their prayer. Is that permissible? Moreover, what is the ruling on making the sound of a slight cough (Ahem) during prayer, with or without an excuse?