Welcome from Michigan !
1 All 04-05's have the same second gear. Some had problems some didn't. Does this fellow know if the bike ever had the "update kit" installed by the dealer ?
2 An "Eastern Beaver" relay kit will save the ignition if it's still good. They are about $80.00
3 Some 04-05 had the output shaft bearing installed backwards so the seal was between the oil and the bearing. This would be rectified if update kit was installed.
4 Some 04-05 had this problem. Also addressed with update kit.
5 The drive shafts hold up good if the rear splines are lubed with moly grease every tire change. The output shaft bearings on my 05 went out at 50,000 miles. Some have more than twice that mileage with original bearings. A bit of a crap shoot there.
If he doesn't know if it has had the update installed, you can get the serial number off the engine and a dealer should be able to tell you if it was installed. I would not buy an 04-05-06-07-08 that didn't have the update. I believe the 09 was the year most of the problems were ironed out. Even an 09 needs an eastern beaver kit.