All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
Briefly, your question could be summarized in the following six points:
A) The ruling of lying and being in the company of liars.
B) What are the sources to learn what is lawful and what is prohibited in Islam and other Islamic etiquette?
C) Is it permissible to possess the wealth of those Muslims by means of cheating and stealing?
D) Does the father have the right to force his children to marry even if they do not want to?
E) What is the proper manner to deal with a father, who humiliates his children, does not keep his promises, and prevents them from continuing their studies?
F) What is the ruling on having cats in the house?
Here are the answers to the above questions, one by one.
A) Lying is among the great sins and it is prohibited in all religions. Allah Says (what means): {Indeed, Allah does not guide one who is a transgressor and a liar.} [Quran 40:28]
The Prophet said: “Beware of lying, for lying leads to vice (wickedness, evil-doing), and vice leads to Hellfire, and a man continues to tell lies, until he is recorded with Allah as a liar.” [Al-Bukhari and Muslim] No doubt that lying weakens one’s faith but does not eradicate it. So, you should avoid those friends who indulge in lying. Instead you should befriend pious and righteous people. Allah Says (what means):
• {O you who have believed, fear Allah and be with those who are true.} [9:119].
• {And keep yourself patient [by being] with those who call upon their Lord in the morning and the evening, seeking His countenance. And let not your eyes pass beyond them, desiring adornments of the worldly life, and do not obey one whose heart We have made heedless of Our remembrance and who follows his desire and whose affair is ever [in] neglect.} [Quran 18:28]
B) As for the way of learning what is lawful and what is prohibited in Islam, truth and other Islamic etiquette; this can be achieved through the Quran, Hadeeth and sayings of trustworthy Muslim scholars. Allah Says (what means): {So ask the people of the message if you do not know.} [Quran 16:43]
Reading good Islamic books and listening to good Islamic cassettes also increase your knowledge. You may use any available means to gain Islamic knowledge.
C) Stealing from and cheating non-Muslims who are in a covenant with Muslims, is forbidden. The Prophet said: “Whoever oppresses a non-Muslim who has been given a covenant, does not fulfill his rights, obliges him to do a task beyond his ability, or takes any of his properly forcefully, I will be his opponent on the day of Judgment.” [Abu Daawood and Al-Bayhaqi]
D) Your father's claim that he is obliged to get you married and your sister before his death and to force you to get married is wrong. Therefore, you do not have to obey him. You are also not obliged to obey him if he commands you to stop your studies, if you believe that discontinuing your education will harm your future and your sister's.
E) As for how to deal with your father, the basic rule is that you must be patient and tolerant with him since the right of a father upon his children is very great. Therefore, one should be kind with his father even if the latter mistreats him. Know that obeying him in legal matters is an act of worship since Allah commands us to be kind to our parents. No doubt that obeying parents always results in goodness. Moreover, you should continue supplicating Allah to bless your father, guide him to what is right and make him steadfast. Keep in mind that the best way to lead him to be a righteous person is to be kind with him.
As for having cats in the house, please refer to Fatwa 82701.
Allah knows best.