

Contacting your previous manager would likely be problematic, especially if you didn’t leave on good terms. I would contact the new hiring manager and explain the situation, and that you would prefer minimal contact with your previous manager, if possible. Were any of the previous issues documented? That could be helpful now. Also if you could, contact any previous colleagues you had a good rapport with and ask them to give a recommendation for you.
Yes, most likely. OP didn’t give details, but maybe that’s the only position in their area they are qualified for that offers a salary that meets their living expenses. There’s also the possibility that the company is overall good to work for and it was just shitty manager/team they were stuck with before. I agree that taking a pay cut can oftentimes be better overall if the new job is easier to handle, but we all have bills to pay, and sometimes the lower salary just won’t cut it.