Pursuant to the statute a fee of 3% is presumed reasonable, which is $6,300. They are allowed to charge more for extraordinary services, such as closing the sale of real property, or preparing an estate tax return. See Florida Statute 733.6171 http://www.flsenate.gov/Laws/Statutes/2012/733.6171
You have a real problem because the legal presumption is that when you put someone else's name on your property you have given them a gift. She's right. She does own half of everything. Take your papers to an attorney. The burden is on you to prove it was not a gift and it's a substantial burden. I'm sorry you have this problem.
You should consult with a New York lawyer as your mother was a resident of New York and that's where the Estate was probated. In Florida it would go half to you and half to your brother's children, in equal shares.
I have encountered this problem before and the only way I have ever helped a client resolve it is through partition which, by the way, always works. Outside of the probate arena I have, several times, had clients try to purchase mortgages from commercial lenders because there is a property they have wanted that is abandoned. We have never been able to get a commercial lender to sell us the paper. I think it must have to do with their regulations or insurance on that paper.
Theoretically that can happen. Ultimately, you are responsible for your outstanding medical bills. Ask your attorney to try to get your outstanding medical bils reduced to leave you with no outstanding bills and put some money in your pocket.
You don't say whether your father had a wife or any daughters. You can run his name through the Clerk of the Court's website to see if an estate was opened. You can check the property appraiser's website to see if he owned any real property. You can check the public records of Miami-Dade County to see if there were any mortgages on any property he owned. If he had no spouse you can open an estate intestate if none was opened. You need an attorney to do this.
You need an insurable interest on a person's life in order to purchase life insurance for that life. Does your daughter-in-law provide you with support? If you own the policy she wouldn't get rights to change the beneficiary.
I agree with Attorneu Corrigan that you can ask those close to her. You can also go through all of her papers. If your mother died without a will the laws of intestate succession apply. http://www.leg.state.fl.us/Statutes/index.cfm?App_mode=Display_Statute&URL=0700-0799/0732/0732.html