Are there vaccinations to prevent septicemia?

Yes. At least 3 vaccines come to mind - hemophilus influenzae type b (causes epiglottitis, meningitis); pneumococcal 13 (causes pneumonia, meningitis) and Meningococcal (causes meningitis).
Yes. Vaccines such as the hib and pneumococcal shots can prevent infections that may cause septicemia.
Not exactly. There are vaccines for influenza, strep pneumonia (the most common cause of pneumonia) and hemophilus influenza (in children) which may prevent infections that can lead to sepsis.