Yusuf Estes, an Islamic Preach, has described the answer in this video link below. In short it is allowed.
There are many Muslims who use Facebook.
Muslims are not allowed in Vatican City.
yes Muslims are allowed agent gelatine.
There are truly no reasons as to why FaceBook should not be allowed.
They go to mosques. However, Muslims are allowed to pray in other clean dry place as home, office, hall, stadium, open air areas, ... etc
No, non-Muslims are not allowed to enter the city of Mecca for any reason as it is considered a holy site reserved for Muslims only.
.................... ermm.. No, Muslims are not allowed to kill (or in other words, taking a life)
Muslims are allowed to eat meat with bones (but of course not eating bones). Refer to question below for what meat allowed for Muslims to eat.
to attack muslims.
No, non-Muslims are not allowed to enter the city of Mecca in Saudi Arabia.
No, only Muslims are allowed to visit Mecca for religious pilgrimage.
No, non-Muslims are not allowed in Mecca, as it is considered a holy city for Muslims and entry is restricted to followers of Islam.