I agree with my colleagues. If he continues to be unreasonable, file a Motion with the Court. Parents are supposed to be flexible when it comes to parenting time. The judge would not be happy with him, and may even order him to pay your attorney fees. Contact a local family law attorney for a consultation.
Sentencing in Florida is based on a scoresheet, and your brother-in-law will receive points on his scoresheet for his priors. The more serious the priors, the higher points they carry. So, yes, the Michigan priors, and priors from any state, will affect his sentence.
I agree with the above answers. More information is needed to answer the questions that you have. You have 20 days to respond to the dissolution petition. You should consult with a local experienced family law attorney. Many offer a free initial consultation.
Sounds like a good case, based on what you are saying. You should schedule a consultation with a local attorney as soon as possible. If you are thinking about representing yourself because you feel you have a good case, don't do it. A conviction for battery can result in a loss of liberty. If you had a very curable form of cancer, you would still go to a doctor.
The child support should be handled in the divorce case. It's much easier and cheaper than having two cases going at once. You should set up a consultation with an experienced local family law attorney.