Ruling on taking a Mus-haf from the mosque, elongating the back excessively during prostration, and fidgeting during prayer

With regard to taking the Mus-haf from the mosque, this is
not permitted, because the Mus-hafs of the mosque should stay in the mosque
and not be taken away. 

With regard to elongating the back excessively during the
prostration, this is not appropriate. Rather the back should be moderate
when prostrating, not stretched out too much and not bent too much.  The
back should be moderate  with the arms lifted up off the ground and the
elbows away from the sides, and the stomach lifted up off the thighs, i.e.,
one should follow a middle way, not stretching it or bending it too much.

 With regard to raising the voice when reciting Qur’aan
before the prayer, you should not raise your voice if there is anyone else
present, rather you should read quietly to yourself, so as not to disturb
other people or distract those who are praying or reading Qur’aan. But he
may raise his voice a little.

 With regard to playing with one’s beard or clothes while
praying, this is makrooh. The Sunnah is to remain still. Allaah says:

“Successful indeed are the
believers.

Those who offer their Salaah (prayers) with all solemnity
and full submissiveness”

[al-Mu’minoon 23:1-2]

 So you have to be solemn in your prayer and not play with
your beard or clothes. A slight movement if necessary is forgiven, but a lot
of movement is not permitted unless absolutely necessary.