Advice for getting ready for a new job

[Hope.for.the.best]

I am thankful that I have got a full-time job while I am still waiting for my PhD defend! I will be working with one of my advisors, let's call him "Ben". I am yet to meet the big boss of the department before "Ben" can issue me an official offer, but he has already indicated me to start by the end of this month. Since "Ben" is totally aware of my background and he has spoken to the big boss, I don't worry too much about the interview. Of course, I still feel nervous! Have you guys got any difficult questions when you got interviewed for a research position? 

My other concern, as detailed in my previous post,

is to break the news to my other two advisors, "Andy" and "Cecilia". Please note that I changed the pseudonyms of my advisors to reflect their genders. Long story short, "Andy" has some conflicts with "Ben" because of research funding and project leadership, and "Andy" took it out on me by intentionally delaying the submission of my dissertation. Not until "Cecilia" stepped in did "Andy" approve my dissertation. "Cecilia" alleviated the situation by asking me to work for "Andy" casually as a research assistant, but then "Andy" changed his mind and got me to work as a volunteer. Coincidentally, something was going on in my family, and I was able to delay "Andy" with compelling reasons. My intention was to wait until I got settled down with "Ben" before getting in touch with "Andy", because "Andy" wishes me to work unpaid for 6 months! Anyway, with the knowledge that "Ben" will employ me, I will offer to help "Andy" out some time this month. I actually don't want to help him, because he had been rude to me when I was writing up my dissertation, and he broke his promise of paying me to work for him. However, "Andy" is my main advisor, and he has to approve any revisions to my dissertation after the defend, so I am trying not to break the bridge too soon. I don't worry about "Cecilia", as she will be equally happy that I work for "Ben", as she has been urging me to hunt for jobs proactively. I don't know how I should explain to "Andy" that I can only work for him for 2 or 3 weeks. I can tell him upfront that I will work for "Ben", but he will not take it well. I know he will find out eventually, but I don't wish to break the news until "Ben" issues me an official offer. My family advise me that I can tell "Andy" that I am looking for jobs, so I can only work for a limited time. If "Andy" follows up by asking what I applied, I can tell him that I will let him know later. What would be the best way to approach this, given "Andy" openly expresses his hatred towards "Ben"?

I am quite worried that "Andy" will withhold signing off my dissertation after the defend. I know you would be thinking that a professional academic should not do that, but given what he did to me before, I believe he is considering that. Yes, I can take it to the school, but I don't wish to do that unless absolutely necessary. You know, although things will be in my favour, it is just unimpressive to complain about my advisor to the school. It leaves an impression that I don't know how to work with others. I can bring that up to "Cecilia" again, but she said she disliked me complaining about "Andy" to her. She wants me to talk to "Andy" in person, but how could I do that when "Andy" was yelling at me? I can tell "Ben" about that, but I don't know how I can approach that appropriately. "Ben" will be my boss for the next few years, so I can't afford to mess things up. 

Any advice is appreciated. Thx!