Hello Kathleen! No you do not have to strip your cabinet before you use chalk paint. If it has a really shinny finish you can use 220 sandpaper to sand the shine down but it is very minimal sanding. Many times you do not have to sand at all. Here's some info for you: https://www.confessionsofaserialdiyer.com/how-to-paint-furniture-using-chalk-paint
No , you don't !!! That is one of the best benefits for using chalk pain !!!
No you don't -- chalk paint will go over virtually any clean surface. You do need to get it nice and clean, but don't need to remove the finish. Good luck!