I'm a Canadian in US on TD visa while my husband is on TN, with two kids in school. My sister is a US citizen and she has decided to petition for me. I planned transferring my Canadian nursing credits to a nursing school in the US. Do I need to change my status to F-1, also after finishing the nursing school can I work while waiting to my status to be updated because my sister is submitting the petition form next week?

TD visa holders are not allowed to work in US. If you want to seek employment after graduated, then you should switch to F-1, so you can work on OPT for a year after graduation.