a) Could be a positive. You understand what it is to be abused, and to heal. They will want to see what you've learned about yourself, and that you could keep a child safe in the future, so no further abusive relationships etc. I know they usually contact exes, but I specifically requested my ex was not contacted, as he was abusive. I had documented evidence of this, and false allegations, which were checked. As he had already lied to authority figures, there was no point in seeking his opinion on us adopting. I also provided references that covered before and after the abusive relationship. I once hit my ex. I didn't volunteer that information, and while my referees knew that, I don't think they volunteered that either. If there is a police record, then I would confess that early on. Remember that adoptive kids may act out, including being violent to you, and you need to be sure you'll never hit them back.
b) Are you wanting to adopt pre-school age? If so, then try and get some experience volunteering at a toddler group. However, most new parents don't get 'experience' with babies before they get them. I think getting experience with 'challenging' children at groups etc when older is more valuable, as it shows you have an awareness of what is coming.
c) Our financial assessment was cursory. Actually, our finances arereally struggling with adoption leave! The big thing is debt management. We have no debts, excpet mortgage, so I suppose this means we're strong enough, as we could borrow if needed. Children are expensive, but most people manage mat leave etc. It's the long term cut in hours if the children cannot manage childcare that are the issue.
Nothing will bar you from adopting, really, it's all about how you handle that, and whether you can talk a good game, in my experience.