2. It's worth every single penny, if you're able to finish it and pass the bar exam. Law school will be so much harder than your current studies. Expect 120 pages of readings every night and these aren't readings that you just read casually. Expect professors to criticize how stupid you are. Expect to fail a few subjects even though you gave your 100%. It all boils down to how badly you want to become a lawyer.
3. and 4. Yes it's ok for someone in his/her mid 30's to enter law school. As to being a nurse-lawyer, lawyers mostly abandon their undergraduate degrees once they become a lawyer. My professor for example who graduated with a degree in agriculture is now in corporate litigation.