A girl wants to become Muslim and conceal her Islam; how should she deal with issues of prayer, hijab and eating pork?

Praise
be to Allah.

Firstly: 

We ask Allah to decree for this girl guidance to His
religion, and to open her heart to Islam, for He is able to do that. 

Secondly: 

Entering Islam is not a difficult matter, praise be to Allah.
Whoever wants to enter Islam, all he has to do is to utter the twin
declaration of faith: Ashhadu an laa ilaaha ill-Allah wa ashhadu anna
Muhammadan rasool-Allah (I bear witness that there is no god but Allah
and I bear witness that Muhammad is the Messenger of Allah). 

If he does that, then he has entered Islam and has become a
Muslim, with all the same rights and duties as any other Muslim. 

Thirdly: 

The basic principle is that the one who enters Islam is
required to follow all the teachings of the religion, doing what is
enjoined, and avoiding what is prohibited. Allah, may He be exalted, says
(interpretation of the meaning):

“O you who
believe! Enter perfectly in Islam (by obeying all the rules and regulations
of the Islamic religion) and follow not the footsteps of Shaytaan (Satan).
Verily! He is to you a plain enemy”

[al-Baqarah 2:208]. 

Ibn Katheer (may Allah have mercy on him) said: Here Allah
instructs His believing slaves who follow His Messenger that they should
adhere to all the teachings of Islam, act in accordance with all its
instructions and avoid everything that it prohibits, to the best of their
ability.

End quote from Tafseer Ibn Katheer (1/565) 

Based on that, if this girl becomes Muslim, she is obliged to
comply with all the commands, which includes offering prayer and wearing
hijab. She is also obliged to avoid everything that is prohibited, which
includes eating pork. 

If she is not able to do some of that or is incapable of
doing any of that, and she fears that she will be harmed or persecuted, and
that they may try to make her give up her religion, then in that case it is
permissible for her to conceal her Islam whilst doing whatever she can of
the obligatory duties and avoiding whatever she can of things that are
prohibited, and whatever she is unable to do, she will be forgiven by the
Most Gracious, Most Merciful, in sha Allah. 

With regard to the issue of prayer, if she is not able to do
each prayer at its proper time, then she may put two prayers together: so
she may pray Zuhr and ‘Asr together, and Maghrib and ‘Isha’ together, and
pray Fajr on time on its own. If she is not able to do that, then she should
offer whatever of the prayers she can on time, and the rest she should pray
whenever she is able to do so, even if the time for any particular prayer
has ended, and even if she is compelled to offer all five daily prayers
together at one time, when she is alone and safe from prying eyes. 

We have previously discussed how a person may pray who
becomes Muslim but is not able to practice his religion openly. For more
information, please see the answers to questions no.
165426 and 100627 

With regard to wearing hijab, if this girl is not able to do
that, she should try to wear clothes that are as close as possible to it,
that she can wear without any fear of persecution. She should cover whatever
she is able to of her body and hair, and whatever she is not able to do,
Allah is Oft-Forgiving, Most Kind. But she should try hard to avoid going
out of the house except in the case of need. 

For more information, please see the answer to question no.
166604. 

Similarly, she should try to avoid eating pork as much as she
can, and eat other things, or she can pretend that she does not feel like
eating it, or other excuses that may be acceptable or that will not cause
conflict with her family and the people around her. 

Over and above all that, she should seek the help of Allah,
may He be glorified and exalted, to make her steadfast in adhering to His
religion, and to avert from her all pressures to make her give up Islam,
both apparent and hidden, and to grant her a way out. 

And Allah knows best.