How can I love the prayer (Salah) and start praying?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
Love for the prayer (Salah) comes when you realize that this world is fleeting and the Hereafter is everlasting. Your prayer is the righteous deed that will comfort you in your grave and be your salvation before Allah in the Hereafter. Do you not wish to attain tranquility in this life and Paradise in the next? Reflect upon your state and do not delay, for life does not wait. We ask Allah to grant us and you steadfastness (Thabat).
What is the semi-circular structure attached to the Holy Kabah?
The semi-circular structure attached to the Holy Kabah is Hijr Al-Kabah (is a low wall originally part of the Kabah) and passing behind it is an obligation while making Tawaf because it is a part of the Holy Kabah. And Allah Knows Best.
Does the clipping of nails nullify ablution?
No, it does not, and it is preferable to wash the hands afterwards.
What is the ruling on seeking forgiveness between the two Friday sermons?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
It is permissible to seek forgiveness (Istighfar) between the two Friday sermons (Khutbatayn), and it does not invalidate the Friday prayer (Salat al-Jumu'ah). Furthermore, it is not disliked (Makruh) to speak before the sermon, after it, or between the two sermons. Likewise, it is not disliked for one who enters during the sermon to speak if there is a need for it, provided he has not yet taken a place and settled into it. And Allah the Exalted knows best.