Single vs twin engine planes
According to NTSB documents I found at:
http://amelia.db.erau.edu/db/ntsbaas.htm
the fatality rate for single and twin engined light planes was not all that much different: 2.31 fatalities per 100,000 flying hours for singles, 2.04 for twins. (13% higher) I didn't find any more recent statistics, but I would think they would stay about the same.
Another point made: 86% of light plane accidents, and 90% of fatalities, were due to to the pilot.
A properly maintained, properly checked-out older plane should be just as safe (maybe even safer) than a new one. The standards are pretty high.