Masturbating in the state of ihraam

Q: A few years ago, I went for Hajj. May Allah Ta'ala forgive me, at that time (I can't remember if it was before or after Arafaat), I committed the terrible sin of masturbation. May Allah Ta'ala forgive me. What is the penalty for this? Also, does that act break ghusl? I doubt I made a ghusl after I committed that act. May Allah Ta'ala forgive me.

Presenting fake certificates when applying for a job

Q: I am working in a gulf country and I given some wrong certificates. I always doubt whether my job is haram or halal. I graduated applied to many companies but they did not choose me as I did not have experience. I gave a record of fake experience and some certificates and I did not show my actual graduation degree. I got a small level job. After getting the job, I informed the interviewer that I had given wrong certificates. Is my income haram or halal? 

Making intention of nafl salaah and fulfillment of a vow

Q: I made a vow to read two rakaats of salaah everytime I do a certain sin and double the amount of salaah if I do it again. I'm doing this in order to help me completely leave the sin out. I want to know, when I read this salaah, can I make two intentions in one? Example, I read this salaah at tahajjud time so I also make intention for tahajjud.

Custody of children after divorce and purdah with step siblings

Q: I am divorced with two children (boy 9, daughter 7). My ex wife, has as I am led to believe, settled down perhaps made or not made nikah with the man I accused her with whilst we were married. I am not sure but I assume he is also divorced, he too has two kids of his own, also a daughter and a son I think maybe a year older than each of mine.

My first question is: What is the most authentic ruling regarding custody of children post divorce? Where and with whom and from what age should they reside with either mum or dad purely from what Shariah explains?

My second question and this is what haunts me: If tomorrow they all decide to move in together and lets say they are indeed married for purposes of this question, how does the mahram thing work? This man, is he mahram for my daughter firstly. Secondly, his children being exposed to my children, I fear abuse, bullying, sexual abuse(possibly! as a parent this thought lingers as they grow older and left alone), and my children being teased by his kids - that they only in that home because my ex wife married their father. Tomorrow if these step brothers or sisters or whatever they will be termed, if their natural father purchases or does something for my kids , they could get jealous or nasty towards my kids, maaf but all of these scenarios seem to be playing out, hence my questions.