Father

Bismihi ta'ala

If you know that your brother would be ok with you using his amanah in a wise and responsible way, and that you would return it back to your brother once he asks for it, then you are allowed to lend that money to your father. 

And Allah knows best.

Bismihi ta'ala

Of course, it is indeed difficult when a son/daughter is faced with such a predicament of dealing with a difficult parent. It is usually inherent within a Muslim that we want to obey and be loyal to our parents.

However, there could be some parents, for whatever reason (mental, social, cultural), who become not just difficult to be with, but intolerable. 

This is all based on the assumption that your judgment, as a son/daughter is absolutely correct, and beyond any doubt based on true evaluation. The reason why I say this is because you might think your father is "dictatorial", but for the wrong reasons.

You might believe he is oppressing you because he doesn't allow you to go out with certain friends, or work in a certain field, or marry a certain individual. In these scenarios, or any other similar scenario, although you believe your father isnt being fair to you, it does not mean he is "dictatorial" or oppressing you. 

That's why circumstances would certainly be different, based on the case each family is in. 

Seeing that you have genuine requests, and legal requests, try to find other avenues of getting your father to cooperate and acknowledge your rights and your feelings. 

Maybe seek intervention, through family members, elders, family counselor, psychologist, and so on. 

You cannot just abandon your father, or disown him, but at the same time you cannot continue allowing your genuine requirements to be ignored. 

Ultimately, an effective tool is always for you to pray for him, and to pray for your situation. 

With prayers for your success.   

Bismihi ta'ala

A "step-father" should aim at trying to become a father figure for his wife's children, and treat them like his own children. One positive way of treating children is by showing affection and loving care, through kissing the children, hugging them, and treating them in the best way possible. 

And Allah knows best. 

Bismihi ta'ala

In this situation, there would not be any problem in the surname he chooses, and hopefully he will somehow be able to find information about his family.

And Allah knows best.

Bismihi ta'ala

This is an circumstantial case that must be looked at individually. Why is the father refusing? Under what pretense? 

It would all come down to negotiation and finding ways of making sure the parents are content. Yes, she is an adult, and she could even be allowed to marry lawfully without her father's consent, but as Muslims we strive towards keeping our parents happy. 

If after negotiation, and intervention from family and elders to convince the father, he is still adamant about his refusal, and it is unwarranted, that is when it would be advisable to involve your scholar. 

We must always remember if we misuse any authority given to us, we will become oppressors and our punishment will be severe. 

And Allah knows best.