Work-life balance and hedge fund interview prep questions from a soon to be PhD grad & single parent

I'm in my mid 20s, and will (should) be graduating this August from my PhD program. My research is in computational physics, and most of my work has focused on mathematics (mostly numerical methods) and software development, with medium exposure to high performance computing and machine learning. I will be going into industry, likely the tech or finance industry. Ideally, I would like to end up in a position where I can write software and build mathematical models.

I don't think I've gotten any recruitment for banks, but I've been getting a lot of recruitment from headhunters and company recruiters for the past year for funds like Two Sigma, DE Shaw, Citadel, Akuna, etc...Quantitative research and developer roles at these places seem most aligned with what I want to do (software + math).

Some questions that I have are:

(1) How is the work life balance of a quant at some of the major firms? I've heard various conflicting opinions on this, and a lot of what I've read are people saying that quants "work 80 hour weeks," "live in their office," "can't raise a family," etc.. and some have also said that quants in the financial industry have the best work life balance.

As a single parent, I would not want to be in the office more than 40-50 hours a week. I'm fine with also working some hours from home during the night and weekends, but I would not want to be in a position where I would need to remain in the office past 5PM or be required to go into the office on weekends. Is it acceptable to work from home outside of normal hours?

(2) I feel a bit intimidated by the difficulty of the interviews. I've heard and read that there are a lot of brainteaser questions asked, and that I should consult resources such as the book "Heard on the Street." I've looked at some of these brainteaser questions, and I don't think I can answer more than half of them, and for the other half, there probably aren't many where I can come up with an elegant solution in an interview session. These questions seem to use very basic grade school math knowledge, but they're tricky.

Any suggestions on how to prepare?

In addition, I have no financial knowledge. The headhunters and recruiters I spoke with told me that this is not a problem, and that some of their clients actually prefer candidates without prior experience.

(3) I'm a bit confused by all the different roles such as quant researcher, quant developer, quant trader, algorithmic trader, algorithmic developer, etc... My impression is there is a lot of overlap between the roles, and each company has it defined distinctly, and a quant researcher at one fund may be doing the same work as a quant developer as another fund. Is this accurate?