First thought...call an insurance company and tell them what you want to do and get a quote for each type. Then, contact some people who own those types of a/c (flight schools, businesses, charter companies) and find out their approximate cost of operation. You can even contact some mx shops and ask how much a normal mx bill is for each type. Then double it...it should be approximately how much your "friend" is looking at to insure and maintain your "friend's" new(er) airplane. Now, add tie down/ramp fees, hangar fees (if your friend is rich), fuel costs, a maintenance reserve for engine overhaul, avionics costs, etc., etc.
As far as best safety record...look in the NTSB files and you should come up with a guesstimate, however, it depends on the pilot and how well maintained the a/c is, for the most part.
Wish your friend good luck. As the saying goes, especially for your higher end airplanes, it's like owning a boat...it's cheaper just to rent it, as they are money pits.
PS not sure of any web sites out there with all this info, but there might be one out there...
