Are vascular conditions a common complication of endocarditis?

Usually not. Endocarditis is an infection of the endocardium(one of the layers of our hearts) and can be quite severe in untreated. Vascular inflammations(or vasculitis) can be a causative factor leading to endocarditis rather than a complication of.
Possible. If endocarditis is not promptly treated vegetations from heart can break loose and clog other arteries.