About the masters degree, if you have the master's degree, most school districts pay a stipend in addition to the salary. I believe you would be considered more marketable with the master's, but you could very likely get a job with just the bachelor's degree.
Certification requirements vary from state to state. You could likely be required to take competency exams in order to receive a certificate for another state. You could also be required to complete some additional coursework. It all depends on the state.
If you look on the internet, state boards often have a wealth of information about the certification process with an out of state certificate. Try searching these sites.